Hey there, long time no talk.
Let’s air this out right now: the Pittsburgh Penguins are getting lucky. Very, very lucky. Like totally, unbelievably, unsustainably lucky.
The Washington Capitals have out-attempted, out-chanced, and generally pushed the Penguins around in this series. The Columbus Blue Jackets kind of did the same thing. But guess what: it’s nothing we haven’t seen before.
Problem: An Over-Reliance on PDO
Let me walk you through a little thing called PDO. PDO is a rough measure of how a team or player compares to the league average in on-ice shooting percentage and on-ice save percentage (looking at an overall team’s PDO can be simplified to simply “the team’s shooting and save percentages”). Given that we are focusing simply on shots on goal (as opposed to shot attempts), we can view shooting percentage and save percentage as two parts of a continuum--a shot on goal is either a goal or it is a save. Given that we have a completely binary relationship between goals and saves, we can make the assumption that on the whole, teams in the NHL should have a PDO around 100.
On the average, the assumption in the stats community is that teams will shoot around 8.5% over the course of a season. It’s a pretty reliable aggregate that includes both high scoring forwards (like Sidney Crosby, who managed 43 goals on 255 shots--good for a 17.3 S%), as well as very low-scoring defensemen (like Brian Dumoulin, who managed just 1 goal on 78 shots this year--a 1.3% conversion rate). This is a trend that is also influenced by special teams: players who get more power play time tend to have slightly inflated shooting percentages compared to players who don’t get power play time.
On the other side of the continuum, we expect goalies to save about 91.5% of the pucks they see. Again, this aggregates all different scenarios: starters might hover closer to 92% while backups often finish the season closer to 90%. Similarly, goalies tend to save a much higher percentage of 5-on-5 shots (somewhere north of 93% based on some quick, back of the napkin calculations), while very good goalies will struggle to stay above 90% while their team is killing a penalty.
While we expect the majority of teams will hover around a year-long PDO of 100, there are certainly exceptions. In most instances we can break the teams that have a higher PDO into one of three categories: Stanley Cup Favorites/Vezina Caliber Goalies/Both. Want an example? Here are the teams that finished with the highest PDO this year:
Washington Capitals | 102.90 | [Both, and Braden Holtby is the current reigning Vezina winner]
Minnesota Wild | 101.76 | [Both, although Devan Dubnyk was robbed of a nomination]
Chicago Blackhawks | 101.44 | [Stanley Cup Favorites, and the closest we’ll likely get a dynasty in the “parity era”]
Columbus Blue Jackets | 101.43 | [Vezina Caliber Goalie, and let’s be real Sergei Bobrovsky is going to win this year, for the second time in his career]
Pittsburgh Penguins | 101.27 | [Stanley Cup Favorites, and you may have heard, reigning Stanley Cup champions]
While there is a decent amount of positive correlation between carrying a high PDO and being considered a “good” team, teams are not typically immune to the principle of regression. Regression suggests that over time, teams will always move towards the average, or in other words, “hot teams will go cold” and “cold teams will get hot”. We have already seen this phenomenon verified with 3 of the teams listed above (the Blackhawks and Wild could not buy a goal in their opening playoff series, while the Blues Jackets couldn’t get a save from their goalie). The phenomenon seems to be repeating again with the Capitals as both their shooting and save percentage have nose-dived since the playoffs started. And trust me, regression is coming for the Penguins, too. The question, then, is when?
Before we go any further, let me get this out of the way now: through 7 playoff games, the Penguins boast a 13.8% SH% and and a 93.6% SV%, that’s equivalent to a 107.4 PDO. It’s unbelievable, and it WILL NOT LAST for the remainder of the Stanley Cup playoffs.
But, looking at other successful teams this season, it’s not entirely impossible that what the Penguins are doing currently can last for a few more games. Take for example the Washington Capitals, who, during an 11-game stretch from January 5 - January 24 never dipped below a single game PDO of 107.84. For that nearly three week stretch the team had a PDO of 112.71.
Similarly, when we compare rollings averages for all of the five teams discussed above, we see extremely large, long swings (of 25 games) where the Capitals held an average in excess of 108, the Wild topped 105, and the Blue Jackets topped 104. By contrast, the Penguins are currently on their “luckiest” streak of the season (looking again at 25 game rolling averages), combining the playoffs so far, plus roughly the last quarter of the regular season, and the team is still only peaking at a 102.84.
Yes, that is lucky, and please don’t misunderstand me: if you’ve watched the way the Penguins have been smashed to bits in pretty much every game they’ve played this postseason, I’m not saying it’s positive. But here’s the thing: operating as though the regular season has no bearing on the Penguins’ current play is to ignore a ton of big, usable data points.
Saying that a team is currently on a lucky streak without also acknowledging that all teams have lucky streaks (and unlucky streaks) is not a particularly prudent way to say that you’re mad that the Penguins are blowing up your bracket.
Hope: Just Beat Washington
The Penguins have to figure out a way to sustain more territorial advantage, they need more time in the offensive zone, and they need to try to tighten up the shots/shot attempts against Marc-Andre Fleury. They have to because it’s been a really, really long time since a team has successfully scored its way to the Stanley Cup. They have to because they aren’t going to score at 14% for another 10 games.
They can also regress to the mean and still beat pretty much any team, except for Washington. After watching the first two games of this series, I feel confident in saying that the Capitals are the best team remaining in the postseason. They’ve been unlucky against the Penguins, but they have not been bad. The Penguins will likely need to squeeze out a little more luck, and then trust that they can return to a possessive, suppressive force like we saw at this time last year. If they do, it could be a very pleasant spring in Pittsburgh.