Blocking Shots and Save Percentage

The question was raised this Spring as to whether better defensive teams have a negative effect on save percentage. The notion was that better teams block more low percentage shots. The shots that make it on goal are therefor more dangerous. I doubt that this is the case, but let's dig into it.

One approach would be to look at where shots get blocked. Unfortunately, the data for this is mostly non-existent. The little data that exists is poor quality and not likely to yield a valid answer. I took the approach of looking at how many shots get blocked and how that relates to various other measures of team defensive performance.

Some Global Numbers

Total Corsi Events: 273180

Total Blocked Shots: 70455

Team with most Corsi Against: Toronto 10627

Team with least Corsi Against: New Jersey 7189

Blues are 4th at 8819

Team with most CA-Blocked Islanders 2724

Team with least CA-Blocked New Jersey 1708

Blues are 21st with 2223

On average, the probability of blocking a Corsi Against is 0.2579068746

Montreal has the highest probability at 0.2910816908

Ottawa has the lowest probability at 0.2278819821

The Blues are 5th at 0.2760751681

Do teams differ in the percentage of shots they block?

I ran a logistic regression to see. Teams do differ significantly.

> LinearModel.1 = lm(bllogit ~ Team, weights=CA, data=Team3yrs)

> anova(LinearModel.1)

Analysis of Variance Table

Response: bllogit

Df Sum Sq Mean Sq F value Pr(>F)

Team 29 2008.21 69.249 4.3414 7.832e-07 ***

Residuals 60 957.05 15.951

Looking at the coefficients, we see that Ottawa, Los Angeles, Detroit, Phoenix, and New Jersey are worse than average, and the Rangers, the Islanders, San Jose, and Montreal are better than average.

Coefficients:	Estimate	StdError	tvalue	Pr(>|t|)
(Intercept)	-1.056876	0.007641	-138.311	2e-16
OttawaSenators	-0.182065	0.042561	-4.278	6.89e-05
LosAngelesKings	-0.148983	0.045969	-3.241	0.001946
DetroitRedWings	-0.122067	0.045479	-2.684	0.009388
FloridaPanthers	-0.111726	0.042757	-2.613	0.011325
PhoenixCoyotes	-0.102334	0.041939	-2.44	0.017656
NewJerseyDevils	-0.109428	0.04772	-2.293	0.025359
BuffaloSabres	-0.077568	0.041098	-1.887	0.063946
CarolinaHurricanes	-0.071811	0.040934	-1.754	0.084488
ColumbusBlueJackets	-0.058729	0.043181	-1.36	0.178901
BostonBruins	-0.046062	0.04343	-1.061	0.293122
ColoradoAvalanche	-0.041534	0.041449	-1.002	0.320349
VancouverCanucks	-0.033905	0.04359	-0.778	0.439725
TorontoMapleLeafs	-0.026719	0.039489	-0.677	0.501252
TampaBayLightning	-0.001522	0.042267	-0.036	0.971403
ChicagoBlackhawks	0.00367	0.044682	0.082	0.93482
EdmontonOilers	0.009968	0.041059	0.243	0.809019
DallasStars	0.018265	0.042059	0.434	0.665652
AnaheimDucks	0.020553	0.042208	0.487	0.628061
NashvillePredators	0.030684	0.04181	0.734	0.465873
PhiladelphiaFlyers	0.039444	0.042661	0.925	0.358877
WinnipegJets	0.040547	0.041712	0.972	0.334918
MinnesotaWild	0.042426	0.042374	1.001	0.320741
WashingtonCapitals	0.041859	0.041655	1.005	0.318983
PittsburghPenguins	0.0441	0.043044	1.025	0.309702
CalgaryFlames	0.072423	0.041333	1.752	0.084852
St.LouisBlues	0.081774	0.044989	1.818	0.074109
NewYorkRangers	0.110108	0.042527	2.589	0.012056
NewYorkIslanders	0.114277	0.041246	2.771	0.007438
SanJoseSharks	0.158662	0.041983	3.779	0.000364
MontrealCanadiens	0.164789	0.042059	3.918	0.000231

Blocks and Team Defense

There is a strong relationship between the total number of shots blocked and the total number of Corsi events against.  (CABperG is Corsi Against-Blocked, i.e., shots blocked, per game, and CAperG is Corsi Against per game.)

There is a small positive relationship between the percentage of shots blocked and the number of Corsi events against per game. Teams that give up a lot of Corsi events tend to block a slightly higher percentage of those events than average teams. (CAperG is Corsi Against per Game and BLPCT is Blocked Shots/Corsi Against).

There is no relationship between the percentage of shots blocked and the number of shots against per game.  (SAperG is Shots Against per Game and BLPCT is Blocked Shots/Corsi Against).

There is no relationship between the percentage of shots blocked and the number of goals against per game.  (GAperG is Goals Against per Game and BLPCT is Blocked Shots/Corsi Against).

There is no relationship between the percentage of shots blocked and team Even Strength Save Percentage.