A little more than a week, our very own Charlie O'Connor wrote an article about the Flyers penalty kill. I was interested in seeing just how good the Flyers penalty kill was, so I went on stats.hockeyanalysis.com and looked at both the Flyers penalty kill stats and the penalty kill stats from teams from the past 6 seasons.
I use mostly Corsi (which is a stat that measures all shot attempts) to asses the performance of the Flyers penalty kill. This is because stats like Corsi and Fenwick have been shown to be the most repeatably and correlate to future success best.
This season the Flyers have allowed the fewest shots, Fenwick events, and Corsi events against at 4v5 per 60 minutes of 4v5 time. Below are the 5 best teams in terms of shot attempt (Corsi against) prevention this season at 5v5.
The Flyers are allowing slightly over 6 shot attempts fewer than the second best team (Vancouver) in the NHL shorthanded. In fact, since the 2007-2008 season, only four teams have allowed fewer than 76.4 Corsi events against. But you'll also notice that the Flyers have a significantly higher corsi for per 60 than any of the other top 5 teams above. At 16.6 Corsi events per 60 minutes, the Flyers take the 2nd highest shot attempts for in the NHL at 4v5, second only to the Winnipeg Jets.
All told, the Flyers Corsi Differential per 60 minutes is roughly -60, meaning that for every minute of 4v5 time, the Flyers' opponent are taking only 1 more shot attempt than the Flyers are. The next closest team's Corsi Differential per 60 is -72.2, or more than 12 shot attempts more per 60 minutes than the Flyers.
This Corsi Differential number is truly spectacular, and it is the 3rd best Corsi differential per 60 minutes of 4v5 ice time in the last 6 seasons.
However, while Corsi differential is nice, it is not perfect, as the team on the power play shoots at a higher percentage than the team shorthanded. To put numbers to the previous sentence, teams on the power play have a corsi shooting percentage (goals divided by corsi for) of 6.46%, while teams short-handed have a corsi shooting percentage of 5.63%. (the corsi shooting percentages is this paragraph were calculated using 4 seasons worth of NHL data).
So it's clearly more important to prevent a shot on the PK rather than taking a shorthanded shot. In order to account for this, I calculated what I like to call expected goals for, expected goals against, and expected goals differential for teams on the penalty kill.
What I did was take the league average 4v5 Corsi SH% and 4v5 Corsi SV% over four years and then multiplied those numbers by team's Corsi for per 60 and corsi against per 60, calculating expected goals for per 60 and expected goals against per 60. I then subtracted expected goals against from expected goals for to get expected goal differential per 60 minutes of 4v5 time.
In other words, expected goal differential per 60 measures what a team's goal differential would be on the penalty kill over 60 minutes assuming they received league average 4v5 goaltending and shot at the league average 4v5 rate.
The Flyers expected goal differential per 60 minutes of 4v5 time was almost exactly negative 4 goals. So in 60 minutes of penalty kill time, the Flyers would be expected to score 4 less goals than their opponent. If this seems very low, it's because it is.
Below are the top 10 teams from the past 6 seasons (2007-2008 season to current season) in terms of expected goal differential per 60.
|#||Team||CF60||CA60||CD/60||expected goals for / 60||expected goals against/60||expected goal differential per 60|
As the above chart shows, the Flyers' Penalty Kill has been one of the best in the last 6 seasons. New Jersey last season and the Red Wings from 2007-2008 come out with a better expected goal differential per 60.
A quick note: that Detroit penalty kill in the 2007-2008 season was remarkable. That's what happens when you have Lidstrom, Chelios, Datsyuk, Rafalski, Zetterberg, Franzen, and Kronwall together to kill penalties. What a remarkable penalty kill group.
The Flyers have a truly elite penalty kill right now. They are one of the best NHL teams in a long time at preventing shot attempts on the penalty kill, and their ability to produce some offense as well contributes to them easily having the best penalty kill in the NHL this season and one of the best of the last 6 years.
It's no surprise then to see 7 Flyers in the top 10 lowest Corsi against per 20 among players with 100 PK minutes or more this season.
What we are seeing is truly fantastic penalty killing, and hopefully it will keep up in the second half of the season.