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Advanced Metrics: PDO and regression to the mean

Explaining why you should ignore player shooting percentages.

Claus Andersen

I'm still not sure everyone has completely internalized the lessons of PDO (shooting percentage + save percentage), so I wanted to look at the relationship between past and future PDO. This plot shows how much future PDO regresses to the mean relative to PDO though a certain number of shots (both for and against.) For example, PDO through the first 1000 shots regresses 87% to the mean over the rest of the season - a team with a 1030 PDO through 1000 shots expects a PDO of 1004 for the rest of the season.


Basically, whatever you think you know about your team's supposed ability to maintain high shooting and save percentages, they are very likely to crash back to league average regardless of how many shots you've observed. Internalize this chart and you can make a lot of money betting against people who are convinced there's mysticism in scoring goals.