PENALTY KILL SV%
There certainly seems to be more randomness and/or potential team effects in this sample than in the even-strength one,.
I think it is likely that playing at even-strength and playing on the penalty kill require different skill sets, at least to some degree, which would explain some of the discrepancy.
a goalie’s contribution at even strength is much more significant than on special teams.
INVESTIGATING SPECIAL TEAMS SKILL
We know that skaters show differences in ability on special teams compared to at even strength, which suggests that 4 on 5 hockey is a different game than 5 on 5.
With a correlation that high, we should be able to use EV SV% to predict PK SV% with some reasonable accuracy.
for the most part goalie performance is similar at even strength and on the penalty kill.
What these results suggest to me is that we should rate goalies based on their performance both at even strength and on the penalty kill.
It does not appear that there is much of a skill difference by game situation for goalies. It is more difficult for all goalies to make a save when their team is down a man, but a better goalie is still generally more likely to make that save than a weaker goalie.
most teams around the league are pretty similar in terms of shot quality against on special teams, although there are probably a few outliers that we need to keep in mind.
SITUATION ADJUSTED SV%
a goalie’s play while his team is killing a penalty is important for evaluation, but that his performance when his team was on the power play was not.
If we ignore the PP shots, a good approximation of the average EV/PK split is 80/20. By assigning an 80% weighting to the goalie’s EV SV% and a 20% weighting to his PK SV% we can quickly adjust for special teams factors.
To simply adjust for special teams factors remember the “80/20 rule”, and you’ll be able to pick out the goalies who have the burden or good fortune of facing heavy or light work on the penalty kill.
IS IT POSSIBLE TO USE PKSV% TO PREDICT SV%
A significant portion of the variation in overall save percentage is variation in short-handed save percentage
PK Sv% and ES Sv% measure largely the same talent, and that the variability of the PK Sv% comes mostly from the small sample sizes.
in the long run, after 150+ games, even strength save percentage is the better predictor of a goalie's future success.
Basically, Even-Strength save percentage, which is measured over a large number of shots, is a significant predictor of future performance, though it must be heavily-regressed to the mean save percentage. SH save percentage, on the other hand, is essentially random. Your best guess of next year’s SH save percentage is the league average.
SPECIAL TEAMS – LUCK OR SKILL
Special teams play is not pure randomness. It can sometimes seem that way over a short sample, for example a playoff series or two, but PK save percentages generally correlate with 5 on 5 save percentages over multi-year samples.
In the long run goalies should be rewarded for persistently strong performance on the penalty kill, but results should be viewed skeptically over a single season.
TEAM EFFECTS & PK SV%
The results are mixed.
team effects are unimportant in relation to PK SV%.
indicates that team effects are relevant.
Interestingly, the data suggests that team effects may be more important at even strength than on the penalty kill.
SHOT BINNING & PK SV%
(Oct 29, 2015)
Most of the goalies haven’t moved very far, but it’s also interesting to note that the curve has flattened. The goalies with the worst stats have seen them improve, and those with the best stats have seen them come down to earth somewhat.
PK SV% AND GOALTENDING ABILITY
(May 2016)
The hypothesis that a goalie’s stats shorthanded are more strongly determined by how their team plays (or the other teams play) when a man down, rather than intrinsic goaltender ability, is entirely reasonable.
This implies that there are team effects beyond just where the shooter can shoot from, since we can already adjust for that. The quality of shots within any location could depend more on team penalty defence.
I have a simple method for testing whether shorthanded stats are more contaminated by team effects than full strength stats. It’s to use the other goaltenders on the same team as a point of comparison. We can see whether correlation between the starters’ stats and their backups’ are more similar in shorthanded situations than in full strength situations.
We can see that there actually is quite a large correlation. The team effect is real.
The team effect exists in full strength play too!
At the start I posed the question: Should we consider shorthanded stats when evaluating goalies?My answer now, is yes. It was yes before, and it is still yes.
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