Jul 192011

An interesting statistical debate sprung up today started by Tom Benjamin who wrote about his skepticism of the Corsi statistic.  In it Tom comments on the fact that Ryan Kesler and Ryan Clowe ranked so highly in corsi in response to Greg Ballentine’s posts at The Puck Stops Here.

Greg’s examples, it seems to me, make a good case against the Corsi statistic. First, both the Kesler and Clowe stories tell us how much influence context has – neither Kesler nor Clowe could have done it playing on a different team or even playing in a different role on the same team. In other words, this is not really an individual statistic.

Of course, this got some in the Corsi crowd up in arms and states that Corsi can’t be used on its own without considering its context.  Gabe Desjardin’s comments on Tom’s post with the following:

Corsi, like any other statistic, needs to be understood in the context of other factors. Sneering at it because, like any other simple statistic, it doesn’t provide a unified measure of a player’s complete value doesn’t contribute anything to the larger discussion of hockey analysis.

Ok, so I am glad we have that cleared up.  Corsi is just a stat without meaning unless you consider the context.  Oh good, now it is on par with nearly every other stat in hockey.  Unfortunately people actually use corsi to actually draw conclusions about players.

Here is the thing that really irks me about some in the Corsi crowd.  They just assume that shot quality doesn’t exist.  An anonymous commenter using the name ‘Name’ writes the following:

Even the basis of corsi, that shot quality always evens out, so we just have to measure shot quantity, is inherently flawed. The strategies and styles some teams play lead to giving up a greater number of shots, but reducing quality ones, whereas some teams strive to block or prevent every single shot, no matter where it comes from. Therefore some players, just by playing on a certain time, will inherently be on the ice for more shots against. It doesn’t mean they’re giving up more quality scoring chances, or making lots of defensive mistakes, or failing to control play offensively.

To this comment Gabe comes back with his favourite response to any challenge put his way:

Name these teams and players. Thanks.

Now that is a fair response, unfortunately he ignores anyone who actually names these players.  The reality is shot quality doesn’t even out.  Some players drive shot quality and some players suppress it.  Some players have a significantly different +/- than corsi +/- year in and year out.  I gave an example the other day in Brendan Morrison.  Here are some other names for Gabe to consider.

Some guys who can drive shooting percentage: Sidney Crosby, Marian Gaborik, Nathan Horton, Bobby Ryan, Martin St. Louis.   Henrik and Daniel Sedin.  Alex Tanguay.  Jason Spezza.

Some guys who can suppress shooting percentage:  Marco Sturm, Travis Moen, Tyler Kennedy, Taylor Pyatt, Shawn Thornton, Chris Drury, Jeff Carter. Torrey Mitchell. Kamil Kreps.

No one in the second group had an opposition shooting percentage above 7.6% in any single season over the past 4 years.  Only a handful of times over the past 4 years has any of the players in the first list had an on ice shooting percentage below 9% and only Bobby Ryan’s 23 game 2007-08 season was below 7.6%.

Now, you’ll probably notice that the first group are all first line players who are expected to produce offense while the second group are mostly third line players asked to shut down the opposition.  It’s difficult to suggest it was just luck that this is how things panned out.  No, some combination of talent and style of play will affect your on ice shooting and opposition shooting percentages.  And again it needs to be stated that shooting percentage is much more highly correlated with scoring goals than corsi.

Jeff Carter is an especially interesting case in that you can in no way argue that he has played in front of especially good goaltending that would drive down his shooting percentage against and yet he has a really slow shooting percentage and yet has one of the highest corsi against of any forward over the past 4 seasons (20.1 corsi events against per 20 minutes over the past 4 seasons ranks 300 of 310) but his goals against (0.753 per 20 minutes)  is decidedly average or even slightly better than average (ranks 139 of 310).

So Gabe, those are some players for you to consider.  I look forward to your response.

Jul 162011

Last night after news came out that Brendan Morrison had re-signed with the Calgary Flames, Kent Wilson tweeted the following:

Morrison back in Calgary. Check out his corsi tied rating fellow stats nerds: http://bit.ly/q1ywUj

The link is to the Calgary Flames 5v5 game tied corsi ratings which show Morrison had a 0.452 corsi rating (Corsi For %) which was dead last on the Flames.  The problem with jumping to the conclusion that Morrison is bad is two fold:

1.  Corsi generally speaking isn’t good at evaluating players.

2.  One year of 5v5 game tied data is not enough to evaluate players, even with corsi.

Lets take a look at Brendan Morrison over the past 4 years and I’ll show you exactly what I mean.  First lets look just at 5v5 any game score situations.

Season(s) CorF% GF%
2010-11 0.484 0.562
2009-10 0.514 0.627
2008-09 0.498 0.569
2007-08 0.430 0.500
2007-11 (4yr) 0.491 0.577

In each and every year the goals for percentage is significantly higher than his corsi for percentage.  His corsi ratings make Morrison look mediocre at best but his goal ratings make him appear to be quite good.  This isn’t a fluke.  It is occurring systematically, every single season, over 4 seasons in which Morrison played for 5 different teams (Vancouver, Anaheim, Dallas, Washington, Calgary).

Now what about 5v5 game tied situations.  Morrison’s 4 year game tied corsi for percentage is 0.482, his 4 year game tied goal for percentage is 0.592 (which ranks 28th of  217 among forwards with at least 1000 5v5 game tied minutes over the past 4 seasons).

Personally, I’d rather have good goal ratings than good corsi ratings.  Morrison is a good signing by the Flames.

Jul 132011

Yesterday I described my player analysis method and used Brad Richards as an example.  Over the next little while I’ll apply my analysis method to a number of players so if there are any players you are interested in seeing my analysis for let me know.  First up is Tim Connolly.  The Leafs lost out on the Brad Richards sweepstakes so lets take a look at how Tim Connolly stacks up.

Let’s start off with a table of what I consider Tim Connolly’s most pertinent information – his 5v5 HARO+ (offense), HARD+ (defense) and HART+ (overall) ratings over the years.

Season(s) HARO+ HARO+ Rank HARD+ HARD+ Rank HART+ HART+ Rank
2007-11 (4yr) 1.171 18/310 0.985 152/310 1.078 31/152
2008-11 (3yr) 1.242 23/319 0.980 158/319 1.111 36/319
2009-11 (2yr) 1.169 67/319 0.975 170/319 1.072 85/319
2010-11 1.045 156/336 0.856 268/336 0.951 220/336
2009-10 1.289 32/338 1.082 100/338 1.185 34/338
2008-09 1.615 2/335 0.941 187/335 1.278 16/335
2007-08 1.322 38/328 0.974 159/328 1.148 55/328

Generally speaking Connolly’s offensive rankings have been well over 1.00 and ranking very highly among all forwards with at minimum 500 minutes of 5v5 time per season and his defensive rankings have been middle of the pack.

Based on Connolly’s offensive statistics he is legitimately a first line center though he has played against relatively weak defensive competition (232/310 in 4 yr OppGA20) as he has played behind Derek Roy in Buffalo.  Last year he played against somewhat tougher defensive competition than he did in 2008-09 and 2009-10 as Derek Roy was injured for more than half the season and he had his worst offensive (and defensive) season so that should be a bit of a concern for Leaf fans.  Still, one season is too short to draw any conclusions so it could just be an anomaly as well but it is something to watch for next season as he’ll likely be given top line duty in Toronto with Phil Kessel and Joffrey Lupul and play against the oppositions better defensive players.

Of interest to Leaf fans who have suffered through several years of poor PP and PK play is Connolly’s special team numbers.  Over the past 4 seasons Connolly has been played a significant role on Buffalo’s power play and the results have generally been good (his 4 year 5v4 HARO+ rating is 1.169).  Connolly has also played a fair amount (about 100 min/season) on the Buffalo PK unit and his performance has been better than what one would expect from his 5v5 defensive numbers.  His 4-year 4v5 PK HARD+ rating is a more than respectable 1.196 so maybe he can play defense when is he trying to stop the opposition from scoring as opposed to trying to produce offense himself.

Based purely on his performance over the past 4 seasons it seems Connolly is a more than reasonable gamble as one could argue he has legitimate first line offensive capabilities and is at least middle of the pack defensively.  The big question of course with Connolly is his health.  Has has played just 48, 48, 73 and 68 games over the past 4 seasons.  The good news is he hasn’t had a significant concussion in several years and his injuries over the past couple of seasons have been non-serious in nature.  If he can be healthy enough to play 70+ games I think a year from now we could look back and say that Connolly was one of the better free agent signings of the 2011 off season, even with a $4.75M cap hit.

Jul 122011

Over the past couple of weeks I have had several comment discussions regarding some of my recent posts on player evaluation and Norris and Hart trophy candidates which centered around which is a better method for evaluating players:  corsi vs goal based evaluation.  A lot of people, maybe the majority of those within the advanced hockey stat community, seem to prefer corsi based analysis while I prefer goal based analysis and I hope to explain why with this post.  I have explained much of this previously but hopefully this post will put it all into one simple easy to understand package.

There are two main objectives for a player when the coach puts him on the ice:  1.  Help his team score a goal.  2.  Help his team stop the opposing team from scoring a goal.  Depending on the situation and the player the coach may prioritize one of those over the other.  For example, a defensive player may be tasked primarily with shutting down an opposing teams offensive players and scoring a goal is really a very minor objective.  Late in a game when a team is down a goal the opposite is true and the primary objective, if not sole objective, is to score a goal.

I think we can all agree on the previous paragraph.  Goals are what matter in hockey so right there we have the #1 reason why goals should be used in player evaluation.  The problem is, goals are a relatively rare event and thus ‘luck’ can have a serious impact on our player analysis results due to the small sample size that goals provide.  This brought on the concept of corsi which is nothing more than shot attempts and is used as a proxy for scoring chances.  The benefit of corsi is that shot attempts occur about 10 times often as goals which gives us a larger sample size to evaluate players.

Continue reading »

Jun 302011

Anyone who knows anything about hockey, save for Florida GM Dale Tallon it seems, immediately thought ‘bad contract’ when they heard that the Florida Panthers had signed Tomas Kopecky to a 4 year contract at $3M/year.  But how bad is that contract?  Well, lets take a look.

Goal based stats (i.e. any stats that requite goals to calculate which is pretty much everything except things like shots or corsi) are heavily influenced by random events over the short term but over the long term tell a much more accurate picture than shot or corsi based stats.  Personally I consider goal based stats over a 3 or 4 year period to be a fairly reliable indicator of a players talent level so lets see how Kopecky compares over the past 4 seasons.

There are 183 NHL forwards who have played over 3000 minutes of 5v5 ice time over the past 4 seasons and Tomas Kopecky is one of them.  Here is how Kopecky compares to his forward peers over that time.

Statistic Value Rank out of 183
Goals For/20 minutes 0.719 150
Goals Against/20 minutes 0.798 106
Goals For % 0.474 157
Opposition GF/20min 0.737 183
Opposition GA/20min 0.760 71
Opposition Goals For % 0.492 183

To summarize, his performance numbers are bad and he has arguably played against the easiest competition of any forward with 3000 minutes of ice time over the past 4 seasons.  On top of that he has never played any significant time on the penalty kill.  Last season he got increased ice time on the Blackhawks top 2 lines and on the PP which boosted his offensive numbers to a career high of 15g and 42 points (previous high was 10g, 21pts) but that is more a result of who he was playing with and not his own talent level.

Kopecky for the most part has been a third line player who got some top six minutes last season because of the post-Stanley Cup salary cap induced fire sale that left the Blackhawks short of experienced forwards. For the past 2 seasons Kopecky earned $1.2M and I don’t think he deserved a raise from that level.  To pay Kopecky $3M over 4 years is probably a $1.5-2M/yr over payment and probably 1-2 years longer than he deserved.  It might be the worst $3M/yr contract ever signed in the NHL but he may be in good company soon because I suspect Maxime Talbot will get a similar contract and his numbers are equally bad, if not worse (though Talbot has played significantly more on the PK than Kopecky).  I pray that the Leafs do not sign Talbot.

Jun 082011

Lance Hornby has an article this morning discussing a report from the New York Daily News that the Leafs are looking to make a trade for the rights to Brad Richards. Two problems with this:

1.  Just last week Brian Burke said “it wasn’t something we are in the process of looking at” (right at end of interview)

2.  Brad Richards agent Pat Morris over the weekend was quoted in the Toronto Star as saying Richards was not willing to waive his no trade clause and will almost certainly wait out June and become a UFA July 1st.

The second point is interesting because in the Lance Hornby article Mr. Hornby wrote:

If Dallas is trying to maximize compensation for Richards’ rights, he must first agree to waive his no-trade clause, a move that agent Pat Morris told the Daily News the Stars have not yet requested. Richards is also awaiting developments with the Stars and their ownership change.

The original New York Daily News article that Mr. Hornby referred two said Pat Morris hadn’t been asked to waive his no trade clause:

“The Stars have not asked Brad to waive his no-trade clause, and at this point in time, he has no intention of doing so,” agent Pat Morris told the Daily News Monday night when informed that a source had said a move to the Toronto Maple Leafs could be completed by the end of this week. “We’re still pointing toward July 1.”

Now it is a shame that Mr. Hornby chose to leave out the important fact that Morris indicated that Richards has no intention to waive his no trade clause at this time but the other interesting point is Morris being quoted as saying that the Stars have not asked Richards to waive his no trade clause.  This contradicts the Toronto Star article over the weekend where Pat Morris said the Stars asked Richards to waive the no trade clause and the request was denied:

“We’ve been asked by Dallas to (waive the no-trade). We’ve analyzed it and, to date, we’re not in the position to give any clearance on a trade,” said Richards’ agent Pat Morris on Saturday.

“In all likelihood, as we go through the remainder of June, we will not be doing so. It isn’t likely that Brad’s mind will change.”

So what is the real story?  Has Brad Richards been asked to waive his no trade clause and chose not to?  Who knows.

May 302011

The general consensus among advanced hockey statistic analyzers and is that corsi/fenwick stats are the best statistic for measuring player and team talent levels.  For those of you who are not aware of corsi and fenwick let me give you a quick definition.  Corsi numbers are the number of shots directed at the goal and include shots, missed shots and blocked shots.  Fenwick numbers are the same except it does not included blocked shots (just shots and missed shots).  I generally look at fenwick and will do that here but fenwick and corsi are very highly correlated to the results would be similar if I used corsi.

The belief by many that support corsi and fenwick is that by looking at fenwick +/- or fenwick ratio (i.e. fenwick for /(fenwick for + fenwick against)) is an indication of which team is controlling the play and the team that controls the play more will, over time, score the most goals and thus win the most games.  There is some good evidence to support this, and controlling the play does go a long way to controlling the score board.  The problem I have with many corsi/fenwick enthusiasts is that they often dismiss the influence that ability to drive or suppress shooting percentage plays in the equation.  Many dismiss it outright, others feel it has so little impact it isn’t worth considering except when considering outliers or special cases.  In this article I am going to take an in depth look at the two and their influence on scoring goals on an individual level.

I have taken that last 4 seasons of 5v5 even strength data and pulled out all the forwards that have played at minimum 2000 minutes of 5v5 ice time over the past 4 seasons.  There were a total 310 forwards matching that criteria and for those players I calculated the fenwick shooting percentage (goals / fenwick for), fenwick for rate (FenF20 – fenwick for per 20 minutes of ice time) and goal scoring rate (gf20 – goal for per 20 minutes ice time) while the player was on the ice. What we find is shooting percentage is more correlated with goal production than fenwick rate.

Shooting % vs GF20 R^2 = 0.8272
FenF20 vs GF20 R^2 = 0.4657
Shooting % vs FenF20 R^2 = 0.1049

As you can see, shooting percentage is much more highly correlated with goal scoring rate than fenwick rate is which would seem to indicate that being able to drive shooting percentage is more important for scoring goals than taking a lot of shots.

Here is a list of the top 20 and bottom 10 players in fenwick shooting percentage and fenwick rate.

Rank Player FenSh% Player FenF20

For both lists, the players are the top of the list are for the most part considered top offensive players and the players at the bottom of the list are not even close to being considered quality offensive players.  So, it seems that both shooting percentage and fenwick do a reasonable job at identifying offensively talented players.  That said, the FenF20 list includes 7 players (Zetterberg, Datsyuk, Holmstrom, Franzen, Hudler, Cleary and Samuelsson) who have played mostly or fully with the Detroit Red Wings and it seems unlikely to me that 7 of the top 20 offensive players are Red Wing players.  Furthermore, the fenwick list also includes guys like Ponikarovsky, Samuelsson, Hudler, Cleary, Williams, etc. who would probably be considered secondary offensive players at best.  From just this cursory overview it seems to confirm what we saw with the correlations – Shooting Percentage is a better indicator of offensive talent than Fenwick For rates.

It is actually no surprise that the Red Wings dominate the fenwick rate leader board because the Red Wings organizational philosophy is all about puck control.

“It’s funny because our game looks at numbers just like other games,” says Red Wings general manager Ken Holland, “but as much value as we assign to puck possession and how essential it is to winning, we really don’t have a numerical value for it that everyone can agree on. Remember when [A’s general manager] Billy Beane started emphasizing on-base percentage in baseball? It wasn’t just a curious number; it changed the game. It redefined the type of player you wanted on your team. It’s coming in hockey; we just have to figure out how.”

This got the pro-corsi crowd riled up a bit as they said “Umm, yeah, we have that stat and it is called corsi” and were a bit bewildered at why NHL GMs didn’t make that recognition.  But anyway, what the above shows is that an organization that focuses on puck control dominates the corsi for statistic so I guess what that shows is that corsi/fenwick probably is a good measure of puck control.  But, as we have seen, fenwick (i.e. puck control) doesn’t automatically translate into goals scored.  There are no Red Wing players among the top 20 in fenwick shooting percentage and Datsyuk is the only Red Wing player in the top 20 in goals for per 20 minutes so while they take a lot of shots (or at least shot attempts), they aren’t the best at converting them into goals.

For me, and I am sure many others, the above is enough to conclude that shooting percentage matters a lot in scoring goals, but for the staunch corsi supporters they will argue that corsi is more persistent from season to season and thus is a better predictor of future performance.  So which is the better predictor of future performance?  The following table shows the correlation between shooting percentage and fenwick rate with the following seasons goal scoring rate.

Year(s) vs Year(s) FenSh% to GF20 FenF20 to GF20
200708 vs 200809 0.253 0.396
200809 vs 200910 0.327 0.434
200910 vs 201011 0.317 0.516
Average 0.299 0.449
200709 vs 200911 (2yr) 0.479 0.498
200709 vs 200910 (2yr vs 1yr) 0.375 0.479

Note:  For the above season(s) vs season(s) correlation calculations, only players with at least 500 5v5 even strength minutes in each of the four seasons are included.  This way the same players are included in all season(s) vs season(s) correlation calculations.

As you can see, when dealing with a single season of data the correlation with GF20 is much better for fenwick rate than for fenwick shooting percentage.  The gap closes when using 2 seasons as the predictor of a single season and is almost gone when using 2 seasons to predict the following 2 seasons.  It seems that the benefit of using corsi over shooting percentage diminishes to near zero when we have multiple seasons of data and though I haven’t tested it shooting percentage probably has an edge in player evaluation with 3 years of data.

Of course, you would never want to use shooting percentage as a predictor of future goal scoring rate when you could simply use past goal scoring rate as the predictor.  Past goal scoring rate has the same ‘small sample size’ limitations as shooting percentage (both use goals scored as it sample size limitation) but scoring rate combines the prediction benefits of shooting percentage and fenwick rate.  The table below is the same as above but I have added in GF20 as a predictor.

Year(s) vs Year(s) FenSh% to GF20 FenF20 to GF20 GF20 to GF20
200708 vs 200809 0.253 0.396 0.386
200809 vs 200910 0.327 0.434 0.468
200910 vs 201011 0.317 0.516 0.491
Average 0.299 0.449 0.448
200709 vs 200911 (2yr) 0.479 0.498 0.619
200709 vs 200910 (2yr vs 1yr) 0.375 0.479 0.527

The above table tells you everything you need to know.  When looking at single seasons both GF20 and FenF20 perform similarly at predicting next seasons GF20 with fenwick shooting percentage well behind but when we have 2 years of data as the starting point, GF20 is the clear leader.  This means, when we have at least a full seasons worth of data (or approximately 500 minutes ice time), goal scoring rates are as good or better than corsi rates as a predictor of future performance and beyond a years worth of data the benefits increase.  When dealing with less than a full season of data, corsi/fenwick may still be the preferred stat when evaluating offensive performance.

So what about the defensive side of things?

Year(s) vs Year(s) FenA20 to GA20 GA20 to GA20
200708 vs 200809 0.265 0.557
200809 vs 200910 0.030 0.360
200910 vs 201011 0.120 0.470
Average 0.138 0.462
200709 vs 200911 (2yr) -0.037 0.371
200709 vs 200910 (2yr vs 1yr) 0.000 0.316

Defensively, fenwick against rate is very poorly correlated with future goals against rate and it gets worse, to the point of complete uselessness, when we consider more seasons.  Past goals against rate is a far better predictor of future goals against rate.

Where it gets interest is unlike offense correlation drops when you consider more seasons which seems a bit strange.  My guess is the reason we are seeing this is because I am just looking at forwards and defense is more driven by goaltending and defensemen and as more time passes the greater the difference are in goalie and defensemen teammates.  Furthermore, forward ice time is largely driven by offensive ability (and not defensive ability) so many of the quality defensive forwards may be removed from the study because of the 500 minute per season minimum I am using (i.e. the group of players used in this study are biased towards those that aren’t focusing on defense).  Further analysis is necessary to show either of these as true though but the conclusion to draw from the above table that, for forwards at least, goals against rates are by far the better indicator of defensive ability.

In summary, it should be clear that we cannot simply ignore the impact of a players ability to drive or suppress shooting percentage in the individual player performance evaluation and so long as you have a full year of data (or > 500 or more minutes ice time) the preferred stat for individual player performance evaluation should be goal scoring rate.  Corsi/fenwick likely only provide a benefit to individual performance evaluation when dealing with less than a full year of data.

May 262011

The biggest hole in the Leafs lineup that GM Brian Burke has been trying to fill for a couple of summers now is the first line center role and that hole in the lineup still exists and needs to be addressed before the Leafs can be serious playoff contenders.  Tyler Bozak was given a chance and failed (though it was probably overly optimistic to expect him to be that level of player) and the hopes of getting a top center in a Kaberle trade also did not pan out (though Colborne is a fine center prospect and may be a quality center a few years from now).  High first round draft pick Nazem Kadri is another option but as of yet hasn’t developed into that level of player.  That said, if nothing changes Kadri is the guy penciled into that role but that wouldn’t be an ideal situation entering the 2011-12 season.  Not only is that putting a lot of pressure on Kadri (who has enough on his shoulders already)  but some within the organization have suggested Kadri might be better suited as a winger than a center.  Regardless of the reason, Burke is desperately in search of a true, established first line center.  Let me take a look at a few of the options.

The only real first line center option in the unrestricted free agent market is Brad Richards.  At 31 years of age he probably has at least 4 or 5 really good seasons left in him and he is a very good playmaker and overall offensive player and likely be a significant boost to the woeful Leafs power play but he is a liability defensively which is a concern for me.  The question is, what are you willing to pay for him as there will be ample competition for his services from Dallas, the NY Rangers and probably others.  Since Burke is against handing out long term deals more than 5 years it may cost Burke 5 years at $8-8.5M per season to get Richards signed.  The Leafs have the cap space to do it, but should they commit that much to Richards?  Would you? Personally, I think if you can get him for $8M or less you do it.  Anything more is getting a bit rich.

The other option for filling the first line center hole is through trade.  Two teams that I can think of that are deep at center and may be (or need to be) looking to make changes are the Flyers and the Sharks.  The Flyers have depth at center, very little cap space, would like to re-sign Ville Leino (but would be at a significant increase in salary) and need to spend some money improving their goalie situation as well (Vokoun?).  They have Jeff Carter, Mike Richards, Danny Briere, James van Riemsdyk and Claude Giroux who have or can play center.  I’d love to see a Jeff Carter or James van Riemsdyk in a Leaf uniform but van Riemsdyk is still on a cheap rookie contract so doesn’t really solve the Flyers money issues and Carter has one of those long term deals that Burke doesn’t like to hand out.  Briere would probably be available and not cost much but his cap hit is $6.5M for four more seasons and he’ll be turning 34 around the time the 2011-12 season starts so he isn’t really someone I see Burke being interested in.

San Jose just suffered another playoff disappointment at the hands of the Vancouver Canucks so one has to wonder if they finally bite the bullet and make a significant change to their core group of forwards.  They have Thornton, Marleau, Pavelski and my rookie of the year pick Logan Couture as players able to play the center position and all are capable of being first or second line centers.  Of the four, Pavelski might be the most ‘available’ but he is also probably the least suitable as a first line center so I am not sure the Sharks are an ideal trading partner for a center.

Continue reading »

May 172011

I wrote an article a few weeks ago about the offensive and defensive contribution (i.e. their HARO+ or HARD+ rating multiplied by ice time) of each position (C, LW, RW, D and G) but I have come to realize that my methodology is incorrect and thus the conclusions are incorrect (at least when looking at league-wide results).  The reason is, in my rating system contribution is evenly distributed among the 5 players on the ice so if I sum up all contributions of all players playing at a particular position I should see each position be given an equal share, and for the most part that is what I saw.  The exception being centers being given more influence and wingers less, this is because players that are listed as being centers often play the wing where as wingers are less often on the ice playing as centers.

The proper method for identifying the contribution a position has on offense and defense is not to sum up their contribution but to look at the variation observed in the players ratings for that position.  Recall that with my ratings a 1.00 is a neutral rating or an indication that the player has no positive or negative effect for that aspect of the game (offense or defense) compared to the expected level of performance when quality of competition and quality of teammates are considered.  Anything less than 1.0 implies a negative impact and anything above 1.0 implies a positive impact.  So, if a position can significantly influence offensive production then we should see a larger variance among centers HARO+ ratings.  The good players at that position will have ratings well above 1.00 and the weaker players well below 1.00.  For positions that do not have a significant impact we should see players at that position have ratings much closer to 1.00 and less variation between the best and worst players.   So, here is what we find.

Position Average StdDev Average StdDev Average StdDev
C 0.918 0.171 0.994 0.116 0.956 0.091
RW 0.927 0.162 1.001 0.096 0.965 0.084
LW 0.939 0.167 0.993 0.099 0.966 0.086
D 0.894 0.095 0.990 0.101 0.942 0.068
G 0.984 0.080 0.992 0.040

The above uses four year ratings (2007-11) and only forwards and defensemen with at least 2000 minutes of 5v5 even strength ice time and goalies with 3000 minutes were considered.  The resulting group included 122 centers, 85 LW, 103 RW, 194 defensemen and 53 goalies.

On offense, the three forward positions have significantly higher standard deviations (0.162-0.171) than defensemen (0.095) which intuitively makes sense.  It means that forwards have a greater ability to influence offensive production than defensemen which is no surprise.  Defensively the greatest variation in HARD+ occurs for centers with defensemen and wingers more or less the same a step below centers and goalies another step back again.  It is possible centers rank ahead of wingers and defensemen in part because they are the ones who take face offs and thus are a major factor in the team gaining control of the puck.

The other thing that you’ll notice is that for HARO+ the average rating is well below 1.00 for both the forwards and the defense.  This probably indicates that the big minute players are the offensive players which makes the average rating (which is ice-time neutral) well below the ice time weighted average (which in theory should be very close to 1.00).  Lets take a look at how the players rate according to total ice time.


Ice time HARO+ HARD+ HART+
>4000 min. 1.042 0.968 1.005
3000-3999 0.906 0.988 0.947
2000-2999 0.864 1.015 0.940
1000-1999 0.784 1.025 0.905

Left Wing

Ice time HARO+ HARD+ HART+
>4000 min. 1.089 0.939 1.014
3000-3999 0.987 0.990 0.989
2000-2999 0.824 1.015 0.920
1000-1999 0.760 1.036 0.899

Right Wing

Ice time HARO+ HARD+ HART+
>4000 min. 1.071 0.963 1.018
3000-3999 0.953 1.003 0.979
2000-2999 0.871 1.008 0.940
1000-1999 0.775 1.047 0.911

For the three forward positions it is clear that the top offensive players get the most playing time while players who get less playing time are slightly better defensive players.  This isn’t really a big surprise as the majority of a team’s offense comes from their top line(s).  The question is, how much does coaching/playing style influence the results.  By that I mean, would first line forwards be better defensively if they were on the third line and asked to play a defensive role as opposed to being on the first line and being asked to and expected to produce offense?  I suspect for most players the answer would be yes.  I suspect the reverse (third/fourth line guys having better offensive ratings if given first line roles) is also true, but probably to a lesser extent.


Ice time HARO+ HARD+ HART+
>5000 min. 0.923 0.988 0.955
4000-4999 0.919 0.997 0.958
3000-3999 0.871 0.998 0.934
2000-2999 0.874 0.974 0.923
1000-1999 0.864 1.025 0.944

For defensemen the best offensive defensemen still get the most ice time, though the variation is much less than seen with the forwards.  Defensive ability seems to have very little variation across ice times until you get to the lower minute players who appear to be more defensive specialists.


Ice time HARD+
>10000 min. 1.040
>8000 min. 1.028
>6000 min. 1.012
>4000 min. 0.992
>2000 min. 0.984

As one would expect, the best goalies are given the most time in goal.  There were 9 goalies with greater than 10,000 minutes of 5v5 ice time and all had ratings over 1.00 except Tomas Vokoun whose rating was 0.978.  According to my rating system, Vokoun is a pretty ordinary goalie which means he is likely one of the more over rated goalies in the NHL because some (or most) consider him elite.  It’ll be interesting to see where he ends up this summer as a UFA and how that team performs next year.  Could Vokoun be another goalie failure in Philadelphia?  Could happen.

May 042011

I am going to combine the Vezina and Hart trophy discussion into one post because the Vezina discussion is going to be fairly short because I actually agree with the nominees.

The three nominees for the Vezina trophy are Roberto Luongo, Tim Thomas and Pekka Rinne.  These are the top 3 goalies in terms of overall save percentage (Thomas first, Rinne second, Luongo third), goals against average (Thomas first, Luongo second and Rinne third) and rank 1, 3 and 4 in my HARD+ 5v5 even strength ratings for goalies with over 2500 5v5 minutes (Thomas first, Rinne third, Luongo fourth).  Incidently, over the past 4 seasons these are the three highest rated goalies for HARD+ for goalies with over 7500 minutes of 5v5 ice time (Thomas first, Luongo second, Rinne third).  These three goalies are probably the top 3 goalies in the NHL today with Thomas leading the pack  Thomas is most deserving of the Vezina trophy this season.

The HART trophy is a little more interesting.  The three nominees are Daniel Sedin, Martin St. Louis and Corey Perry.  Let me address each of these three individually.

Corey Perry – A couple weeks ago I write an article explaining why I didn’t think Corey Perry was as valuable to the Ducks this season as in past seasons.  In short, while Perry put up some great individual numbers and anyone who scores 50 goals in the NHL is doing something right, he accomplished this at the expense of his line mates and his overall team performance.  Of the 116 players with greater than 1000 even strength 5v5 minutes Corey Perry ranked 46th in HARO+ (1.164), 90th in HARD+ (0.852) and just 69th in HART+ (1.008).  Great individual numbers but his teammates performed better when not with him.  Is that indicative of someone deserving the title of “Most Valuable Player”?  I don’t believe so, though I believe there is a great chance he’ll win because he scored 50 goals and put up big numbers down the stretch to help the Ducks make the playoffs.

Martin St. Louis – St. Louis had another great season and I do believe that St. Louis is the most important player for the Tampa Bay Lightning, and has been for many years now.  Overall he ranked 16th in HARO+ (1.335), 36th in HARD+ (1.022) and 14th in HART+ (1.179).  I would not suggest that he is a bad nominee, but there might be better ones.

Daniel Sedin – Of the three nominees, Daniel Sedin is the only one I would consider listing as a top three candidate.  He ranked  a close second (to Nathan Horton) in HARO+ (1.474), ranked 13th in HARD+ (1.135) and ranked fourth in HART+ (1.305).  The only negative against Sedin is that there are many other players who play against better competition.  Sedin’s opposition goals for ratio is just .501 which is well below some others worthy of HART trophy consideration.

Here are a handful of others I would consider worthy of HART trophy consideration:

Jonathan Toews – Toews has the third best HARO+ (1.465), the 17th best HARD+ (1.117) and ranked 5th in HART+ (1.291).  Toews numbers are very close to Daniel Sedin’s but it can be easily argued that Toews played against tougher competition (.509 opposition goals for percentage vs Sedin’s .501) and unlike Sedin, Toews kills penalties too.

David Backes – Backes scored 31 goals and 62 points and led all NHL forwards with a +32 rating (one behidn league leader Chara) and he did this on a weak St. Louis Blues team and like Toews, he also plays when the team is short handed.  If he played with better players his individual stats would likely be much better but because he plays on a weak team his performance largely gets unnoticed.  What is impressive is he accomplished this while having the highest opposition goals for per 20 minutes and goals for percentage.  Backes’ performance puts him 4th in HARO+ (1.449), 9th in HARD+ (1.199) and  second overall in HART+ (1.322).  By all acounts Backes had a great season, even if the goal and point totals don’t quite match the league leaders.

Anze Kopitar – I am not sure if everyone realizes how good of a 2-way player Kopitar is.  He puts up good offensive numbers but he  has also defensively sound and kills penalties.  This past season he ranked 10th in opposition goals for per 20 minutes and ranked 15th in opposition goals for percentage so he is trusted to play against the leagues best players and the results are there to back that up.  This past season Kopitar ranked 5th in HARO+ (1.427), 4th in HARD+ (1.239) and first in HART+ (1.333).

The problem with HART trophy voting is they largely choose players who put up the best individual offensive numbers but in general they neglect to take into account defensive ability and responsibility.  In Toews, Backes and Kopitar we have three quality offensive players who also play solid defensive games against top players in the NHL and are given the responsibility to kill penalties.  The other player I would suggest is worthy of consideration for the HART trophy is Zdeno Chara who was clearly the best defenseman in the NHL this past season as I discussed in yesterdays Norris Trophy post.

So with all that said, I expect that Sedin or Perry will win but my top five HART trophy candidates would be: Daniel Sedin, Jonathan Toews, Zdeno Chara, Anze Kopitar and David Backes and if pushed to make a pick I’d probably choose Sedin ever so slightly over Toews and Chara.