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Corsi and Score Effects

I'm actually going to look at what I believe are called "Fenwick" numbers today – total shots directed at goal excluding blocked shots.  Because of rink bias, Fenwick numbers actually correlate better with winning than Corsi numbers do.  First, a little rationale for why we want to look at Fenwick and Corsi numbers.  This table shows how many playoff and non-playoff teams exceeded 50% Fenwick ratios on the road, at even-strength, with the game tied:

 

Spots Teams Make Ply
Playoff 112 51 45.5%
Non-Playoff 98 8 8.2%

 

These numbers are for 2001-2009.  For the years where missed shots are missing, I just used shots on goal.  It's clear to me – and hopefully clear to you – that playoff-bound teams are much more likely to dominate the shot counts in the clutch minutes of their games.  It's not a guarantee, but it certainly was the path Detroit and New Jersey used to succeed over the last decade, and a low percentage is certainly a red flag for any team with cup aspirations.

Here are the overall (home and away) Fenwick ratios for the playoff-bound teams in 2009-10 by lead:

Team -3 -2 1 0 1 2 3
chi 63.0 70.4 63.2 58.6 53.9 55.0 54.8
det 55.4 60.5 54.2 54.0 48.8 50.2 39.6
pit 61.8 54.3 57.4 53.7 50.0 46.7 40.5
bos 48.3 53.3 55.5 53.6 49.9 46.5 48.3
pho 58.7 58.0 52.0 52.1 48.9 43.6 49.4
nj 55.5 60.3 52.2 52.1 49.2 48.2 51.5
sj 56.5 59.6 54.2 51.6 45.9 43.1 49.2
nsh 55.7 54.9 56.3 51.6 48.3 46.5 36.4
phi 59.8 57.8 55.4 51.6 49.9 47.4 46.3
ott 53.7 55.0 57.4 51.2 49.1 48.8 52.0
was 61.6 59.2 58.2 50.9 46.8 49.9 46.9
la 56.1 62.9 56.9 49.8 47.3 41.5 39.5
buf 46.5 55.6 53.8 49.6 47.5 44.4 47.3
van 61.5 66.4 55.9 49.2 46.1 42.3 42.5
mon 50.2 57.1 49.2 46.7 43.5 42.7 52.7
col 59.7 54.4 52.8 44.5 43.0 39.3 36.1

 

That's a lot to chew on, but there are two takeaways:

1) Chicago is dominant

2) Montreal and Colorado are in big trouble

One issue with this table is that because playoff teams have tended to win games, they're in the lead and tend to shoot a bit less than they would if they'd won fewer games.  We can correct the total for score effects:

 

Team Actl Corr SE
chi 58.3 59.3 1.0
was 51.3 52.2 0.9
sj 50.6 51.1 0.5
col 45.8 46.3 0.5
nsh 51.2 51.5 0.3
pho 51.2 51.4 0.2
nj 52.0 52.1 0.1
pit 52.8 52.9 0.1
van 50.9 51.0 0.1
phi 52.2 52.3 0.1
det 53.0 53.0 0.0
buf 50.0 50.0 0.0
bos 52.5 52.4 -0.1
la 51.2 51.0 -0.2
ott 52.1 51.9 -0.2
mon 47.4 47.2 -0.2

 

So the "true" Fenwick ratio for playoff teams is, for the most part, higher than the actual ratio.  Similarly, teams with poor records needed to get adjusted in the other direction:

 

Team Actl Corr SE
cgy 50.9 51.4 0.5
nyr 49.5 49.8 0.3
ana 47.2 47.5 0.3
stl 50.1 50.2 0.1
fla 45.8 45.7 -0.1
nyi 48.1 48.0 -0.1
cls 46.9 46.8 -0.1
tb 47.3 47.1 -0.2
car 47.7 47.5 -0.2
dal 48.4 48.1 -0.3
atl 48.0 47.5 -0.5
min 48.9 48.3 -0.6
edm 45.4 44.6 -0.8
tor 53.0 52.1 -0.9

 

Incidentally, for those who still don't believe even-strength shot ratio is important, note that only two teams with a ratio below 50% made the playoffs, while only three teams above 50% missed the playoffs.  Two of those teams were Calgary and St. Louis, both of which would have easily made the playoffs if they were in the Eastern Conference. 

The only real outlier in our entire sample is the Toronto Maple Leafs, who, for most of the season, had a goaltender who was so bad that they couldn’t afford to stop being aggressive even when they had the lead. Or something like that – Toronto, for some reason, outshot their opponents when they had a two-goal lead on the road. I can’t come up with a reason why they played like that, but nothing is rational in Toronto these days.

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