The Useless +/- Stat
James Mirtle from From the Rink and the Edmonton Journal’s David Staples are questioning the usefulness of the +/- stat and maybe abandoning it altogether. I have wrote about this here before and I have to agree, it is the most useless stat in the NHL. The big flaw in it is that a player gets penalized if he plays with a group of bad players or gets a big benefit if he is playing with a group of really good players, regardless of how good or bad the individualy player is.
James Mirtle goes on to refer to sites such as Behind the Net which has better stats such as on ice vs off ice comparisons. But these stats, while significantly better than +/-, are still flawed. The idea is that by comparing a players +/- (or goals for or goals against individually) when he is on the ice to his teams +/- when the player is off the ice you will factor out some of the unfair benefits or penalties a player receives in his +/- stat based on who the player plays against. But even this doesn’t really solve the problem.
The problem still exists because Chris Draper is having his on ice stats compared to off ice stats that are racked up by guys like Zetterberg, Datsyuk, Holmstrom, etc. why a guy like the Islanders Trent Hunter has his on ice stats compared to Mike Comrie and Mike Sillinger. Chris Draper might be a very good defensive player, but when you compare his +/- to the rest of his all-star stacked team mates, most of whom he doens’t get the benefit of playing with, his on-ice to off-ice ratio stats become misleading. The goal of Behind the Net’s ratio numbers is to eliminate the unfair benefit of playing on a great team. The problem is, if a player who plays on a great team, such as Draper, never gets to play with his great team mates, like Datsyuk, Zetterberg, Holmstrom, Franzen, Cleary, etc. and instead plays with pretty ordinary players, such Maltby and Drake, then you end up factoring out a benefit that never existed in the first place.
When considering all players who have played 60 games with at least 10 minutes of even strength ice time per game last season, David Perron, Viktor Kozlov, Dany Heatley, Michel Ouellet, and Pavel Datsyuk came out as the top 5 rated forward in Behind the Nets ‘Rating’ statistic which is the players +/- rating compared to the team. The bottom 5 were Radek Bonk, Alexander Semin, Kris Draper, Jarret Stoll and Mike Fisher.
Now, can you honestly believe that Kris Draper, who had the most short handed minutes of any Red Wing player is the second third worst defensive player in the NHL, especially considering that the Red Wings had an 84% penalty kill success rate? Would the Ottawa Senators use Mike Fisher, supposedly the 5th worst rated player in the NHL, for nearly 3 minutes a game on the PK? Would the Edmonton Oilers have used Jarret Stoll, the 4th worst rated player according to Behind the net Rating, for the same amount of time on their PK unit? Conversely, if Ouellet is such a good player, why did he get zero PK time last year? Same with Perron on the Blues and Kozlov on the Capitals.
Clearly Behind the Net’s on ice/off ice +/- ratio ratings system is still failing to really tell us the whole story even if it is probably a bit better than straight +/-.
A year or so ago I worked on developing my own ratings system which admitidly is far more complicated than +/- or Behind the Net’s ratio system and while still far from perfect I am confident is much more revealing. What I have done is taken into account who a player has played with and against and tried to factor out any benefits they might have by playing with better than average players or against worst than average players or penalties they may get by playing with worse than average players or against better than average players. Instead of looking at how his team plays when he is off the ice vs when he is on the ice, I look at how his teammates play when they are playing with him vs how they play without him. The result is a player will get a good rating when he consistently makes his team mates better when they play with him vs when they aren’t playing with him. I also take into account PP and PK time which I think is important when evaluating a players value.
The results can be seen at Stats.hockeyanalysis.com and select the links under ‘Player Rankings”. I calculate both an offensive and defensive rating plus an overall rating which is independent of ice time and then an overall value, which factors in ice time. A player with a high rating and plays lots of ice time will get a really good value. In the ratings, a rating of 1.00 is approximately average while anything above is above average and anything below is below average.
In my ratings, Kris Draper had a 1.23 defensvie rating and a 0.98 overall rating which is far from the bottom 5 in the NHL. When compared to his all-star team mates, Draper doesn’t look to good, but when compared to the average NHLer, Kris Draper can more than hold his own. Mike Fisher had a 0.93 defensive rating and a 0.94 overall rating and Stoll had a 0.92 defensive rating and a 0.90 overall rating which are both a bit below average but are both far from the worst in the NHL. Interestingly, Ouellet and Perron and Kozlov still do quite well in my ratings so it seems Behind the Net’s flaws might be more significant at the bottom of the list than at the top.
I need to point out that my ratings are still not perfect. I still haven’t found a way to successfully factor out the impact of the goalie and players who play on teams with a bad goalie may have their defensive stats overly impacted in a negative way and players on teams with great goalies will have their defensive stats biased to the positive side). Also, the more a team juggles their lines the better and more accurate my ratings should be because it makes for better with team mate, with out team mate comparisons. But overall I believe they are reasonable and I personally have more confidence in them than Behind the Net’s on ice/off ice ratings comparison. At some point I hope to revisit my ratings system and see if I can improve it further.