Power play shooting percentage: is it repeatable?

[Cunneen]

Much research has been done to show how even strength shooting percentage is ridiculously random, on both the individual and team level. As a result, shooting percentage cannot be used to predict future success, whether in the same season or in different seasons.

So I tried to do the same test for shooting percentage on the power play.

Here are the results for the past 6 years


Team Sh% Sh% Sh% Sh% Sh% Sh%
2013 2011-2012 2010-2011 2009-2010 2008-2009 2007-2008
Anaheim 14.21 10.99 13.68 11.78 13.6 11.27
Boston 10.13 12.82 9.63 11.61 15.07 13.59
Buffalo 9.84 10.76 12.44 12.14 14.19 11.79
Calgary 15.03 12.73 13.28 11.27 11.52 11.55
Carolina 9.48 11.96 11.75 12.63 12.55 14.06
Chicago 11.05 10.66 16.29 12.95 13.62 12.03
Colorado 11.18 11.78 11.71 12.37 11.78 11.54
Columbus 10.11 8.77 8.01 11.52 9.72 11.65
Dallas 12.82 12.69 11.61 12.04 11.11 14.52
Detroit 13.25 11.37 13.67 11.23 13.97 11.57
Edmonton 16.86 16.07 12.06 13.35 13.39 15.11
Florida 14.05 12.8 7.53 11.23 10.39 11.11
LA 16.2 11.55 10.17 14.32 12.62 11.28
Minnesota 12.56 10.31 13.73 14.1 14.14 13.11
Montreal 13.71 9.31 12.82 14.4 12.61 16.52
Nashville 12.57 15.92 10.61 10.39 10.62 11.41
New Jersey10.75 12.42 8.01 13.47 9.92 9.67
NY Islanders14.43 14.33 10.88 9.84 12.5 10.5
NY Rangers11.56 12.34 11.67 12.47 9.16 10.28
Ottawa 10.33 13.68 12.38 11.7 14.15 14.55
Philadelphia14.64 13.17 11.44 13.36 17.99 15.19
Phoenix 10.33 11.11 11.11 11.23 11.32 13.62
Pittsburgh 14.98 12.02 11.03 11.14 12.71 13.5
San Jose 11.02 11.61 11.15 13 15.1 11.5
St. Louis 13.78 12.1 13.14 11.95 13.93 13.06
Tampa Bay13.87 12.5 12.32 11.55 12.69 13.16
Toronto 14.86 13.87 11.8 8.64 11.78 12.42
Vancouver 12.18 12.63 16.46 13.95 11.21 11.6
Washington20.5 12.05 9.52 16.23 16.25 14.25
Winnipeg 10.59 14 12.64 11.75 14.66 11.61


Here are the r^2 values between each season

2007-2008 to 2008-2009: .20931

2008-2009 to 2009-2010: .10631

2009-2010 to 2010-2011: .00753

2010-2011 to 2011-2012: .00651

2011-2012 to 2012-2013: .05983

Pretty clear that power play shooting percentage cannot predict future power play shooting percentage across seasons.

So why does this happen?

Well first thought may be that roster turnover affects this data. There may be some truth to that, but I would argue that the players that play on the power play (the core of any team) are pretty constant from year to year. You don't see teams letting go or trading power play forwards or defenseman as much as third line and fourth line players.

What I believe is that shooting percentage is just very random from year to year, similar to even strength shooting percentage.

Regardless, power play shooting percentage clearly is not repeatable and seems to be far more influenced by luck than anything else. As a result, teams should not focus on power play shooting percentage when looking at their success on the power play and instead should focus on other metrics than can be proved to be repeatable.

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[overpass]

Regardless, power play shooting percentage clearly is not repeatable and seems to be far more influenced by luck than anything else. As a result, teams should not focus on power play shooting percentage when looking at their success on the power play and instead should focus on other metrics than can be proved to be repeatable.

Can you really expect a team to shoot as well if it stops focusing on shooting percentage and starts trying to maximize shot volume? Consider that all of the teams who generated the data you analyzed were probably focusing on increasing both their shooting percentage and their shot volume.

 

[Cunneen]

Can you really expect a team to shoot as well if it stops focusing on shooting percentage and starts trying to maximize shot volume? Consider that all of the teams who generated the data you analyzed were probably focusing on increasing both their shooting percentage and their shot volume.

My point is not that team's should just throw pucks at the net as often as they can on the power play. Shot quality definitely exists. But data shows that teams do not have that much control over their shooting percentage.

This means that team's should not bank on their power play performing just because their power play shooting percentage is really high the year before (I haven't yet looked at in season predicition, but I would probably say that the same concept applies). I don't quite know what is the best predictor of success from year to year on the power play (that is my next study), but it certainly is not shooting percentage.

And while I haven't looked at individual players, its probably safe to assume that power play shooting percentage is very random on the individual level. If this were the case, then teams/general managers could use this to not trade/pick up players expecting X amount of power play goals if they had a very high power play shooting percentage the year before.