St. Louis 99.2
Tampa Bay 99.0
New Jersey 97.8
As of March 3, 2011
Three of the top four teams in the league in points are also three of the top four teams in PDO, and four of the five teams with the worst PDO can all currently be found in the league's basement. There's obviously something that can be learned from PDO, so what is it?
PDO was introduced by Vic Ferrari a few years ago and while nobody remembers what it stands for, everyone knows how it's calculated. Simply add save percentage to shooting percentage, and you should wind up with a number relatively close to 100.0 (or 1000, as some people prefer to present it). And technically you're supposed to use even-strength numbers only, something we'll skip for simplicity.
While further description of PDO is outside the scope of this article (but can be gained from either Tyler Dellow or Corey Pronman),it's clear to see why PDO is so closely associated with the standings. When we're talking about upwards of 5000 shots for and against per season, even a fluctuation of 1.0 means 50 goals, which is easily enough to knock a strong team out of the playoffs or to push a weak team in.
While it's been previously established that team PDO has a strong tendency to 100.0 due largely to the heavy dependency that shooting percentage has on luck (about 75%), Gabriel Desjardins discovered that the presence/absence of skilled players can sustain a team at a significantly different level for several consecutive seasons. Therefore, it is probably best to compare each team to their established PDO levels instead of 100.0 before predicting jumps or slides.
Comparing each team's PDO to their previous season, here are the biggest jumps in PDO since the Lockout.
Largest increases in PDO since the Lockout
Team Season PDO (change)
Colorado 2009-10 +4.3
Philadelphia 2007-08 +3.7
Boston 2008-09 +3.2
Four other teams had jumps of at least 2.0, and for all seven, PDO dropped an average of 1.7 the following season. So instead of predicting a slide based on having a PDO over a certain level, it may be more appropriate to predict slides for teams who suddenly jumped to that level.
Only two of the seven teams sustained their high PDO the next season, the 2008-09 Philadelphia Flyers, who went up a further 0.2 and the 2007-08 Pittsburgh Penguins, who went up 0.4. Why was the improvement in the Flyers and Penguins more permanent? The Flyers had Mike Richards and Jeff Carter coming on to the scene, and the Penguins had Sidney Crosby, Evgeni Malkin, Jordan Staal and Marc-Andre Fleury. It stands to reason that their increase in PDO was a genuine and explicable improvement in skill as opposed to a luck-based fluctuation.
Today, there are only three teams riding high with increases over 2.0: Philadelphia, Minnesota and Boston, all three of whom are simply bouncing back from seasons where their PDO dropped by at least 2.0. Boston is one of only two teams since the Lockout to suffer drops in PDO greater than 3.0.
Largest decreases in PDO since the Lockout
Team Season PDO (change)
Boston 2009-10 -3.8
Nashville 2007-08 -3.5
Both Boston and Nashville were victims of a rather nasty regression to the mean. Boston was regressing from the third-biggest jump since the Lockout, and Nashville was sliding back from a season where their team shooting percentage was 11.8%, the second highest of any team in the new NHL, and over 3.0% higher than anything they've achieved since 2007-08.
Apart from these two teams, there have been twelve teams to have their PDO drop by at least 2.0. In the fourteen combined cases, they averaged a PDO bounce back of 1.1 the following season, and only two continued to drop, the 2008-09 Calgary Flames and the aforementioned Predators.
In Calgary's case, it could very well have been the coaching style of Mike Keenan, under whom Miikka Kiprusoff and other Flames netminders managed to stop only 90.1-90.6% of the shots, despite stopping 91.5-91.7% under Darryl Sutter and Jim Playfair previously, and 91.6% under Brent Sutter afterwards.
Right now, there are four teams with a PDO lower than last season's by at least 2.0. In the case of Washington (which was explored in more detail by Neil Greeberg), Colorado and possibly San Jose, they are just regressing to the mean after a big jump, but this is probably good news for the New Jersey Devils, whose PDO has never changed by more than 0.6 until this season's streak of bad luck.
Anyone who would like to study this further, send me an email for a spreadsheet of every team's shooting percentage, save percentage and PDO since the Lockout, and keep me posted on anything you discover.
Robert Vollman is an author of Hockey Prospectus.
You can contact Robert by clicking here or click here to see Robert's other articles.