What does PDO (and Corsi) really mean?

What does PDO really mean?

A lot of people analyzing hockey stats will tell you that the Leafs are extraordinarily lucky given that they get so heavily outshot in nearly every game. Though I'll agree that there is some luck involved in their 'inflated' record, I don't think there is nearly as much based on luck as some would suggest.

Most of the sabremetricians.. sabremetrologists... Sabres goalie coaches will tell you that PDO is a good indicator of how lucky a team is. If a team has a PDO that it's too much higher or lower than 1000, then that team is unusually lucky or unlucky.

So what is PDO? It's the sum of a team's SV% and SH%. So if a team has average goaltending and scores at an average rate, then that's a team even on the luck scale.

I used to see the logic in this, but the Leafs have been laughing in the face of stats like Corsi and PDO and logic for going on 115 games now. The Leafs over this span have a PDO of 1025, which means they are lucky.

But let's break it down for a second; what would you call a goaltending tandem with a SV% .917? I would say that's a slightly above average tandem. Also, what would you call a group of skaters that scored on higher percentage of shots? I don't know about you, but I would call them better-skilled and more opportune skaters.

So what do you get when you add above average goaltending to better-skilled and more opportune skaters? Hmmm... I would call that a better-than-average team.

So by that logic people could say that the Leafs are a better-than-average team, but what I keep hearing is that they are a luckier team. The thing is that they have actually sustained a relatively high PDO for 114 games now, which would suggest that this is just what they are. So I would say that PDO can be used as a decent indicator of luck over small sample sizes, but a sustained PDO over a larger sample can be used as a decent measure of overall skill.

Secondly, the way they give up so many shots and take so few of their own, the Leafs are doomed to fail eventually. And I would agree with that if not for what I wrote in the first half of this post.

For example during the game in Anaheim on March 10th, I saw a few instances where the Leafs had set up in the Ducks' zone at even strength and had them hemmed in there for over a minute at a time. The funny thing about this sustained offensive time was that on each occasion, the Leafs only registered 1 shot, but each shot did look dangerous. So this is zone time that would not have been accurately measured by Corsi, and since very few shots were taken added to the fact that over half the Ducks' shots were unscreened and came from a different area code, their PDO would have remained high as well.

What I see when I watch the games and look at the stats is a team that is very good at creating dangerous scoring chances, decent in finishing them and very lucky to have skillful goaltenders. I would say most of the Leafs' luck can be attributed to having a couple of elite forwards (JVR & Kessel), good supporting forwards (Kadri, Bozak, Raymond, Lupul), a good offence first D-core (Reilly, Franson, Phaneuf) with a couple of ok defensive Dmen (Gleason, Gunnarson) and a great young goaltending tandem (Bernier & Reimer).

By that logic there is actually room to be luckier...

So what does this all mean? It means that hockey is not baseball. It also means that PDO and Corsi, though they are good predictors, are really only a caption to the big picture of the game.

There is so much more to hockey than just Corsi and PDO and quality of opposition etc. It is also skill, confidence, intimidation, arrogance, frustration, patience, truculence and pugnacity. Let's not get caught up in trying to define a team by numbers when the numbers only account for part of the story. There will never be enough stats that could ever give you the whole picture, because just when you think you have all the numbers to predict it all... John Scott will score again.

PS - this was written before the SJ game is a fan community that allows members to post their own thoughts and opinions on the Toronto Maple Leafs and hockey in general. These views and thoughts may not be shared by the editor of

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