Monday, December 5, 2011

Advanced Statistics: for dummies! PDO

Advanced stats in hockey are not to be taken as law or gospel, but they can help confirm or deny what you're eyes see while you watch. Advanced stats are very helpful because they help us see things that our brain might not be recognising, for instance, many Leafs fans thought that Keith Aulie was Jesus on skates last year, meanwhile advanced stats tell us he was more like the water that Moses easily parted. This is not a post about Keith Aulie, but a series of posts explaining in layman's terms what advanced stats are, and why they are helpful.

The first stat i would like the start with is a stat called PDO. PDO is the addition of team shooting percentage (every shot resulting in a goal / every shot taken) and team save percentage (every shot against resulting in a save / every shot against) while a specific player is on the ice. This stat is always 1.000 league wide because every shot that goes in, a goalie lets in. Let's say for example that, league wide the average save percentage is .915, this would mean the league wide shooting percentage was 8.5 resulting in a 1.000 PDO for the league (.915 + .085 = 1.000). Since league wide, the stat is always at 1.000, you can expect a specific player's PDO to come up, or regress to 1.000.

So, if a player has a team 10.9 percent SH% and a .930 SV% while he is on the ice this player's PDO would be 1039. While you are watching this player play you are going to see a lot of goals scored, and not too many against, thus making them look good, but their PDO number is showing you that they may be getting lucky while on the ice. In this instance they would be getting lucky in both senses, only a .891 SV% against is very below average and sure to normalise, and a .930 SV% is very high, so high that only one goalie in recent memory seems to be able to pull off. So something that you may expect for this player is to see a decline in assists and goals, and see an increase in goals against.

PDO is a great stat to look at when you are starting to think that a certain player sucks, or that he is the best player in the league. This stat will tell you when every shot his line takes is going in, and temper your expectations so that once they go goalless for a couple games you aren't burning your Kessel jersey. This stat will also tell you that for your player that is getting horrendous goaltending, and no one on his line can buy a goal, it's going to turn around.

PDO can be tracked at

Throw down any comments or questions you may have in the comments section!


  1. Great explanation. I remember reading a description of PDO and how it is used for analysis at Pensburgh and it didn't help me at all like this did.

    Thanks dude.

  2. Hey no problem! Glad I could help, keep coming back for the next ones!

  3. Your denominator in team shooting percentage should be "every shot taken" not "every shot resulting in a save"