Fancy math: The Toronto Maple Leafs penalty kill

Cam Charron
December 13 2011 04:01PM

The Toronto Maple Leafs penalty kill over the last five seasons, for lack of a better term, has been absolutely brutal. Every possible stone has been overturned: the system is bad, the personnel is bad, so what is there left to change?

So, this, naturally, popped up over at Arctice Ice Hockey:

Quoth James Mirtle: "It's comical at this point how poor the Leafs PK continues to be. I don't even know what more there is to write on it after three years."

Toronto's Save % at 4-on-5:

2007-08: 855 (28th)

2008-09: 824 (30th)

2009-10: 848 (28th)

2010-11: 835 (30th)

2011-12: 829 (28th)

Are the Toronto Maple Leafs a statistical anomaly? Has Toronto suffered through bad save percentage on their penalty kill because they've employed terrible goaltenders? That can't really be right, since Jonathan Willis looked at the numbers and found that goalies saw little year-to-year correlation in their penalty-killing save percentages.

So maybe there is an ability for teams to control shot quality. After all, it would explain how lousy Toronto is. I, in turn, mined up all the data I could find over at Behind The Net to see if I could prove that good team save percentages or shooting percentages were sustainable.

And I failed.

However, let's step back for a minute. Let's look at the top worst team save percentages on the PK in the last few years:

YEAR TEAM Sv%
2009 TOR 82.3%
2009 DAL 83.2%
2011 TOR 83.5%
2011 COL 83.7%
2010 NYI 84.3%
2009 PHX 84.3%
2010 NSH 84.6%
2009 DET 84.6%
2010 TOR 84.7%
2009 ATL 84.8%

The 2009 Toronto Maple Leafs, proprietors of three of the ten worst goalitender save percentages since the Behind The Net era began back in the 2007-2008 season. But they are also the only team among them who appear on the list twice.

Worth noting, however, that the '11 Avalanche, '10 Islanders, '09 Red Wings and '09 Thrashers all changed their goaltenders the following season. The Leafs have as well, but they inexplicably kept riding Jonas Gustavsson and Vesa Toskala when it was apparent that they weren't NHL-material.

Here are the ten best:

YEAR TEAM Sv%
2009 MIN 93.3%
2009 NYR 92.0%
2011 FLA 91.6%
2010 STL 91.5%
2010 BUF 91.3%
2010 BOS 90.9%
2011 VAN 90.6%
2011 OTT 90.6%
2010 PHX 90.5%
2011 MTL 90.3%

Again... no goalie appears on the list twice, however now, it appears that specialty teams favour the goaltenders the more recent the years get. Eight of the ten best goalies are from the two most recent seasons of the four we have available. However this could also be because there are fewer called penalties , which meant there was more time for teams to regress in the 2008 season.

In case you're wondering, the correlation co-efficient from one year to the next over the last four years has been .015. There just isn't enough evidence to prove that at the NHL level, teams can consistently perform better or worse than the median as far as preventing quality shots goes.

As for shooting percentages, well, I found the same thing, The year-to-year correlation for shot percentage at the team level was .087, so while there may be a bit of repeatable ability there, the outliers simply don't repeat the following season(the co-efficient for shots rates at the team level is .301, so it's a much better predictor of future success).

I did a little experiment. While adding team shooting and save percentages at even strength is a good way to figure out a team's luck, I also added a team's powerplay shooting percentage to its penalty killing save percentage. That number, which I'm calling ST PDO (special team's PDO), is pretty much total guesswork:

YEAR TEAM ST PDO
2009 MIN 107.5%
2011 VAN 107.2%
2009 PHI 107.1%
2008 EDM 104.5%
2008 MTL 104.5%
2010 STL 103.7%
2009 WSH 103.7%
2008 PHI 103.6%
2011 OTT 103.4%
2010 BUF 103.4%
2008 MIN 103.3%
2009 S.J 103.3%
2010 CHI 103.1%
2011 MTL 103.0%

YEAR TEAM ST PDO
2010 TOR 93.8%
2009 DAL 93.9%
2009 TOR 94.3%
2010 NYI 94.3%
2010 NSH 94.5%
2009 PHX 95.4%
2011 COL 95.5%
2009 N.J 95.6%
2011 TOR 95.7%
2011 CBJ 95.8%
2011 N.J 95.9%
2010 DAL 96.4%
2008 ATL 96.4%
2009 COL 96.7%

If special team success was a repeatable skill for a team, how come no team keeps doing what they're doing when they have a high ST PDO? Why didn't the 2010 Minnesota Wild or Philadelphia Flyers keep doing what made them successful? Those team went from 5th and 9th in their conferences to 7th and 12th, respectively.

Again, though, the only team that is consistently low on the chart are the Maple Leafs, who don't have a goaltender. New Jersey and Colorado aren't there for repeating years and made coaching changes since those days.

These are the total outliers. The majority of teams had years fall between 97% and 103% on ST PDO. I just included the teams that saw a large percentage. Big swings in ST PDO were able to influence the standings. The 2009 Dallas Stars and Montreal Canadiens saw big dips in the standings after seeing big swings in ST PDO, while the two biggest risers in four years were enough to give the 2011 Vancouver Canucks the President's Trophy and the 2010 Phoenix Coyotes a playoff appearance after being 13th a season before.

So I checked the ST PDO for this season. Two notes:

  1. The Vancouver Canucks are still extremely successful, so draw whatever conclusions you want to from that.
  2. That said, so are New York's and Boston's, who had respective ST PDOs last season of 98.5% and 100.5%, so who knows if they've actually changed anything.

Here's a chart with all the special team's ST PDO for this season:

TEAM ST PDO 5v4 SH 4v5 SV
VAN 107.1% 16.1% 91.0%
NYR 105.9% 14.6% 91.3%
BOS 105.6% 14.5% 91.1%
N.J 104.5% 9.8% 94.8%
ANA 103.4% 11.9% 91.5%
EDM 103.4% 15.6% 87.9%
PIT 103.0% 12.4% 90.6%
TOR 102.4% 19.6% 82.9%
NSH 102.4% 13.3% 89.1%
FLA 102.3% 12.2% 90.1%
MIN 102.2% 11.0% 91.2%
CGY 101.8% 12.8% 88.9%
ATL 101.8% 13.0% 88.8%
L.A 101.7% 9.6% 92.2%
NYI 100.6% 13.1% 87.5%
OTT 100.5% 13.5% 87.0%
BUF 100.4% 10.9% 89.5%
DAL 100.3% 13.0% 87.2%
PHI 99.4% 15.3% 84.1%
PHX 99.2% 8.2% 91.0%
T.B 98.1% 11.7% 86.5%
WSH 97.9% 11.0% 86.8%
DET 97.7% 11.8% 85.9%
CHI 97.5% 11.1% 86.4%
STL 96.0% 9.7% 86.3%
CAR 95.9% 9.6% 86.3%
MTL 95.6% 6.4% 89.2%
COL 95.1% 13.1% 82.0%
S.J 93.5% 7.8% 85.7%
CBJ 85.3% 6.8% 78.5%

The Canucks, Bruins and Rangers are pulling away in goal differential this season from much of the pack, although, scary thought, so is Detroit, who are getting below-the-norm goaltending at 4v5. San Jose is also a sleeping giant here, who are low in both categories on specialty teams.

Also, as far as the Leafs are concerned, the reason they aren't feeling the effects of their horrible penalty kill this year is because they also sport the highest team shooting percentage in 5v4 situations. If the Leafs problems are goaltending-based, that's another huge anvil for Toronto as we head forward.

Anyway, we had 6 teams last year outside the 97-103% range, and we have 17 through mid-December this season. Certainly there are still some teams who have room to rise and fall.

So, this was a failed attempt to "prove" that teams could continue to shoot or save at high rates over the course of seasons. Any additional commentary or thoughts are welcomed.

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Cam Charron is a BC hockey fan that writes about hockey on many different websites including this one.
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