Puck Luck and the 2013-2014 St. Louis Blues

PDO is a simple but quirky little stat. You add together a team's shooting percentage and their save percentage. That's all. Typically they move the decimals around by multiplying that result by 10 so you end up with a number somewhere between 900 and 1100. [Moving the decimal annoys me to no end which is why I was excited when one of the new stats sites Extra Skater finally kept the decimal in the correct place when computing PDO. It just makes more sense to me.] However, in this post, we are looking at player PDO and not team PDO. They use the same formula for players, but use the shooting percentage and save percentage for the team when that player is on the ice. For instance, if Jackman is on the ice for 20 Blues shots and 2 of them find their way to the back of the net, his On Ice Shooting Percentage will be 10%. If Halak makes 9 out of 10 saves while Jackman is on the ice, then Jackman's On Ice Save Percentage will be 90%. Jackman's PDO for that game will be 100.0 or 1000.

What does this tell us? As Hawerchuck over at Arctic Ice Hockey wrote back in 2011:

...you get a statistic that is almost 100% luck. How can this be? Surely there are players or lines who are higher-percentage finishers than others and can also play adequate defense? I'm not saying there aren't but for the vast majority of NHL regulars, a high PDO in one season comes crashing down the next. And many players with high one-ice shooting percentages get them by cheating offensively, which leaves them susceptible to higher-percentage opportunities against them at the other end of the ice.

Luck. Pure luck. But luck that can be forecast to some extent. Since we know high PDO (above 1000) is unsustainable and low PDO will eventually return back to 1000, we can take a look at the trends over time to try to forecast who might be expected to improve this season compared to last, and which player we might expect to not do as well as previous seasons.

What does this all mean?

Take a look at the legend at the top of the chart. The thin horizontal blue line is set at 1000 which is the PDO "threshold". This is the level at which over time players and teams average out. The higher a player is over 1000 the more exceptional they are playing on the ice, and vice versa. But keep in mind, this is not indicative of skill as much as "puck luck". The thin yellow line is that players average across the seasons. The shaded area shows the player's trend over time by season.

For players whose yellow line is below 1000 I think we could forecast that their PDO might increase during the upcoming season. For players whose yellow line is above 1000 we could forecast that we might not expect as good of play from them this season.

At the very top of this list is Alex Pietrangelo. He had a dramatic dip in his PDO back in 2009 that has skewed is overall average. Overall, his PDO has been relatively consistent since then, except for a slight drop last season. So what can we expect this season? At the least, more of the same. Best case scenario? His PDO trends upward this season and maybe even peaks over 1000.

Vladimir Sobotka has been trending just below the 1000 mark for his PDO, with a slight drop last season. His overall average is a healthy distance from 1000 which leads me to think that based solely on this one stat, we might be able to expect some good things from Sobotka this season.

The Umlaut Overlord (it is easier to type that than try to spell his name correctly) is an interesting case. His overall average for the past three seasons is below 1000 but his PDO has been trending upwards. Does this mean he might have a spectacular season? Perhaps? But not if he spends his time on the 4th line or warming the bench in the suburbs of Chicago (seriously...I hate that the Blues minor league team is now in Chicago). Also, keep in mind it is a relatively small sample size of only 3 seasons.

At the bottom of the list is Adam Cracknell. He has been playing great for the Blues the last three seasons, when he has played. He only played in about half of the regular season games last season and only 2 games the season before. Expect Cracknell's PDO to drop the more ice time he has this season, though it doesn't necessarily mean he'll necessarily be playing worse.

T.J. Oshie will be interesting to watch. His overall PDO average is right at 1000. While his PDO dropped last season, it could drop even more before it goes back up. Or it could very well happen the other way. Who knows? Flip a coin. That is probably going to be as good a predictor of his performance as anything at this point in the season.

By the way, there are some players missing. I did not include any player that had played less than 3 seasons with the Blues. Also, if you can't see a blue or yellow line, that is because one is covering the other.

PDO is a fun stat to consider and look at and it does provide context to a player's performance and lets us know if a player is on a hot streak or has had a run of bad puck-luck. Since I've put these forecasts out there, we'll check back in during the Olympic break to see how well this quick PDO analysis held up during the first half of the season.

Here's to a great 2013-2014 season for the Blues!

Long live The Note!

For more information about PDO please check out this great post by Cam Charron over at Backhand Shelf.