Can someone please explain to an ignoramus like me PDO?
http://www.sportingcharts.com/nhl/st...rcentage/2014/
Quote:
PDO is an advanced statistic in hockey that combines save % and shooting % in an effort to measure overall performance of a team and highlight teams with outsized "luck".
The basic idea is that teams on average should be around the 1.000 level as each shot is either a goal or a save teams that are relatively higher are producing above expectations and should regress back to the 1.000 level and teams that are relatively lower are producing below expectations and should regess up to the 1.000 level.
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Honestly, this doesn't make sense to me. Why is shooting percentage and save percentage tied together in a metric that should equal 100? Anything above this is 'good luck' and everything below that is 'bad luck'?
Could it not be possible that having good players and/or a good system increase both metrics, without any luck involved? I'm sorry, but if I have a team with Carey Price in net, Ovechkin on a wing, Stamkos in the middle, and a guy like Subban blasting bombs from the point I would without a doubt expect my "PDO" to be higher.
Let's see the top 3 teams for this metric:
Montreal
Tampa
New York
Well, that makes fairly good sense, given the composition of the teams, no? Sure, Calgary at 5 and Ottawa at 6 may be the two outliers in the top 10, but again, to me it proves nothing.
Let's look at the bottom 3 teams:
Arizona
Edmonton
Carolina
Yep, makes sense there, given their performances and team makeups. You might argue that having Eric Staal, Jeff Skinner and even a surging Elias Lindholm may be a surprise, but the Canes have been terrible at scoring goals, and their save percentage is mediocre at best since all their goalies haven't been that great, and their defence (especially post-deadline) has been terrible.
It seems like a completely fabricated metric. Why should it equal 1.00? I understand they are trying to quantify luck here, but this is just stupid to me. Sounds a lot like the RGI metric here!
Also, CORSI - sure, some stuff is predictive and interesting, but it doesn't really measure possession now, does it? If you are saying you are measuring possession, then measure possession. All you are measuring is shots. Nothing more, nothing less.
Does the number of shot attempts correlate with possession? Sure it does, but not always! There are teams that will do their best at just getting shots to the net and hoping for the best, and others that try to make more plays. Surprise surprise - getting a tonne of shots to the net does NOT correlate with scoring chances, and it will lower your PDO (at least the shooting percentage side of things) to the 'average'.
I think there are some interesting things to take out of CORSI, but it is overblown and overused in my opinion. There are too many exceptions. PDO is only interesting as a gauge to see how good your players are - nothing more, nothing less (IMO).