Jan 302011
 

Yesterday there was a post on the Behind the Net Blog which discussed the Washington Capital’s 2009-10 even strength shooting percentage of 11.0% and the conclusion was that it must be mostly luck which resulted in a shooting percentage that high.  But was it?  It was noted in the article that in 2007-08 the Capitals shot at 8.1%, in 2008-09 they shot at 8.2% and this season they are shooting at 8.2% again.  So clearly 2009-10 appears to be an anomaly, but was it a luck driven anomaly or something else?

Most people in the hockey analysis world have been using a simple binomial distribution to simulate luck so I’ll do that here too.  The thing is, if the Washington Capitals were really a 8.2% shooting team last year, the chances of them shooting 11.0% or better on 2045 shots is a mere 0.0042%.  That kind of luck we should expect once every 8000 NHL seasons.  In short, we can be pretty confident that the Capitals 11.0% shooting percentage wasn’t all luck driven.

So the next question is, how much of it is luck, and how much can we attribute to other factors?  Well, let’s assume that their good luck was significant to the point where there would only be a 5% chance they could have experienced even more luck.  We can do this by constructing a binomial distribution using centered on a shooting percentage where the chance of producing a shooting percentage of >11.0% is 5%.  The result is shown in the following chart:

The far left vertical line is the number of goals that Washington would produce if they had an 8.2% shooting percentage and the far right line is their actual shooting percentage.  The center vertical line is the theoretical shooting percentage we would need to meet the 5% luck conditions outlined above.  Under this scenario one could suggest of the extra 57 goals that Washington scored above what they would get if they shot at 8.2%, 22 of those goals can be attributed to luck and 35 can be attributed to skill.

But what if we assumed the Capitals were extremely lucky and there was only 1% chance of having greater luck.  Under that scenario their true talent level would be 9.49% shooting percentage and 26 goals would be due to skill and 31 would be due to luck.

Regardless of how you want to look at it, a significant portion of the Capitals elevated shooting percentage was likely due to non-luck factors, be they actual talent, playing style, score effects, etc.

Jan 092011
 

The Los Angeles Kings have signed Jack Johnson to a 7 year contract extension which will pay him $3.5 million the first 3 seasons and $5 million the final four seasons with a cap hit that works out to a cap hit of $4.36M per season.  So the question is, is it a good deal for the Kings?  I am not sure it is.

First, let me start off by saying that I really don’t watch the Kings that much so I haven’t seen Jack Johnson play all that much.  My comments here are based purely on a statistical analysis.  For some of you that makes these opinions objective, for others it probably means you think I am out to lunch, how can you fairly evaluate someone without having watched him a lot.  So be it.

So, lets start off with the good.  Over the past couple of seasons he has significantly improved his offensive output, especially on the PP.  In 2007-08 he had 3g, 11pts in 74 games.  In 2008-09 he had 6g, 11pts in just 41 games.  Last season was a bit of a breakout year for him as he posted 8g, 36pts in 80 games and this season he has taken that up another level with 4g, 31pts in just 41 games.  That said, the majority of his point production increase this season has been on the power play where he has 3g and 21 points or 68% of his points vs 36% one year ago.  Of course, his PP ice time has risen from 2:48 a game to 4:02 a game so that was a factor.  His PP performance so far seems to be coming at the expense of Drew Doughty who has seen his PP points drop significantly this season from last.    He had 23 even strength points last season and is on pace for 20 this season so even strength there is no real improvement.

Now for the bad, or should I say ugly.  It can be shown that statistically he has been and still is one of the worst defensive defensemen in the NHL.  Of the 110 NHL defensemen who have had 200+ minutes in 5v5 game tied situations, Johnson ranks 109th in my HARD+ rating system with a 0.588 score (a 1.00 score would be an average defenseman) which evaluates a players defensive performance while taking into consideration the quality of both his teammates and the opposition he plays against.  This isn’t anything new.  Of the 92 defensemen who played 400+ 5v5 game tied minutes last season Jack Johnson finished dead last in my HARD+ rating.  If you are one of those people who prefer to use fenwick/corsi, Jack Johnson finished 86th of 92 in my FenHARD+ rating last season.

If you don’t fully understand my HARD+ rating systems that’s OK, you can take a look here to see all Kings defensemen sorted by FenF% (Fenwick For / (Fenwick For + Fenwick Against) and you will see that last season he was dead last among Kings defensemen with 50+ minutes 5v5 game tied.  To to be fair, he is a bit better so far this season in FenF% but that isn’t the case in GF% (goals for / (goals for + goals against)).  It seems the coaches are questioning his defensive responsibility as well as his short handed ice time has been cut from 1:35 a game last year to 1:07 a game this year.

No matter how you look at the numbers, Jack Johnson has probably been  somewhere between bad and dreadful defensively thus far in his career and while he looks to be developing into a good, or maybe very good, offensive defenseman, particularly on the PP, one has to wonder if making a 7 year big $$ commitment to him was a wise decision.  It probably isn’t unusual for defensemen to improve their defensive skills as they age but Johnson has a long way to go to even become an average defensive defenseman.  It was a risky signing in my opinion that the Kings may regret down the road.  It’s a lot to pay for a PP specialist, especially when you already have Doughty, a much better player in all aspects of the game including probably the PP, already on your roster.

Jan 062011
 

The score of a game influences how a team plays.  When a team is trailing they play a more aggressive offensive game, when they are up a goal or more, they play a more defensive game.  The question I answer today is, how does score influence a teams save percentage.

To answer this question I looked at the past 3 seasons of 5v5 even strength save percentage data when the score is tied, when the team is up by a goal, when the team is up by 2 or more goals, when the team is down a goal and when the team is down by 2 or more goals.  For each team and score category I have a data point for 2007-08, 2008-09, 2009-10 as well as a three year average (2007-10).  For each score category I sorted from lowest to highest save percentage and then plotted them on one chart and got the following:

As you can see, when the game is tied generally produces higher save percentages than when a team is leading or trailing and when a team is trailing their save percentages are at their worst.  This is probably not surprising as a team will open up its game in hopes of creating offense but also puts them at risk defensively.  Now, what that table doesn’t tell us is if all teams experience the same score effects or, for whatever reason, do some teams actually have improved save percentages when trailing or leading.  The following chart shows each teams 3 year save percentage by score ordered from lowest 5v5 game tied save percentage.

The majority of teams have the majority of their leading or trailing save percentages below the game tied save percentages but there are a number of occassions where that doesn’t occur and they are mostly related to up2 or up2+ save percentages.  The only teams that had a down1 or down2+ save percentage above game tied save percentage were:

  1. Dallas – Down1: 92.51% vs Tied: 91.74%
  2. Detroit – Down1: 93.05% vs Tied: 92.16%
  3. Pittsburgh: Down2+: 92.87% vs Tied: 92.78%
  4. Minnesota:  Down2+: 93.21% vs Tied: 92.89%
  5. Florida: Down1: 93.92% vs Tied: 93.23%

On average, teams had their down 1 goal save percentage 1.3% lower than their game tied save percentage and their down 2+ goal save percentage 1.90% lower than their game tied save percentage.  The average team save percentage at 5v5 tied is 92.7% vs 91.4% down a goal, 90.8% down 2+ goals, 92.2% up a goal and 92.1% up 2 goals.  Tailing can have a sizable negative impact on save percentage where as leading can have a minor negative impact.

So what does this mean?  It means we need to be careful when evaluating goalies (and probably shooters to some extent) based on save percentage (special team effects) or even 5v5 even strength save percentage because the game situations a goalie has been exposed to will influence the goalies save percentage.  A goalie on a weak team will have his save percentage lowered simply because his team is going to be trailing more often and be forced to take chances to create offense and thus he will be exposed to tougher shots where as a goalie on a good team who leads the game more than they trail a lot will not face as many tough shots.

One interesting thing I noticed while doing all this was the Toronto Maple Leafs up by a single goal performance over the last 3 seasons.  While they were middle of the pack 5v5 game tied (16th in 3 year 5v5 game tied save percentage), they were downright horrific when they got up a goal.  They just couldn’t hold a lead.  The three worst single season save percentages when up a goal were the 2009-10 Leafs, 2008-09 Leafs, and the 2007-08 Leafs so they were three for three there.  Over the course of the past 3 seasons the Leafs posted an 88.4 save percentage when up a goal which was 3.44 standard deviations from the mean.  Next worse what the Ottawa Senators who were well ahead of them at 90.8, a mere 1.23 standard deviations from the mean.  The good news for Leaf fans is their 5v5 up a goal save percentage is much better this year: 95.6% (better than any team in any of the last 3 seasons), 97.2 for Gustavsson and 93.9% for Giguere so they are much better at maintaining the lead.  Unfortunately this season they can’t score well enough to get them a lead to protect.