PDO – part II

My two previous posts have looked at how much team shooting percentage and team save percentage regress to the mean in consecutive seasons. Now I’m going to do the same for PDO. As a quick reminder PDO is calculated as follows:

PDO = 10 X (Shooting percentage + Save percentage)

As the premiership average sh% is 21.8% and sv% is 78.2% the average PDO is

PDO = 10 X (21.8 + 78.2) = 1000

To determine how much PDO regresses to the mean on a season by season basis the plot below is of PDO in ‘year 1’ (eg 2000-01) against PDO in ‘year 2’ (eg 2001-02)

So PDO regresses ~62% to the mean from season to season which mirrors very nicely what was seen for both sh% and sv% (as would be expected given that it’s a product of these numbers).

So to conclude, teams with an extreme PDO have been strongly affected by luck and will regress strongly towards the mean of 1000, even over the short term.