Goalie Stats 3 - Save Percentage
- tmlblueandwhite
- Dec 24, 2022
- 4 min read
Updated: Jan 28, 2023
EV SV% WHILE TIED
Outshooting appears to have little effect on save percentage at even strength in a tie game.
In the least, EVSave% removes scenarios where a goaltender is giving up an inordinate number of goals because his team is constantly short-handed or poorly executes the PK. This general equality reveals itself in the actual EVSave% numbers, which more bunched together than standard SV%.
League average EVSave% last season was .920 and most goalies hovered right around there.
ES GOALIE SHOT QUALITY PERFORMANCE
What’s most significant about using this many years worth of data is the relative insignificance of shot quality in overall performance. The variance in expected save percentage is so low that 90% of a goalie’s observed performance is due to other factors – primarily skill. If you’ve seen a goalie play for three or four seasons, you can be pretty confident that his actual save percentage is a good measure of his true performance
REPLACEMENT LEVEL SV%
(Oct 2009)
In my mind, there are two main skills embodied in save percentage: even-strength (5v5) and short-handed (4v5).
The replacement level save percentage is .938 at 5v5 and .899 at 4v5.
I can then determine the approximate contributions of every goaltender relative to replacement level over the past two seasons.
to estimate Wins Above Replacement.
LUCK & SKILL IN NHL GOALTENDING SPREAD
(May 2010)
the theory that there is very little skill variation among NHL goaltenders is not completely crazy: even-strength save percentage was almost three-quarters luck, with the team contributing a minuscule 2% and the goaltender himself contributing only 26%
If we were to look at every minute played by a goaltender in the NHL regular season over the last 36 months, almost 50% of the variance is still due to luck.
While these results are interesting, the more important question is whether it’s sustainable.
There is some sustainability in even-strength save percentage, almost none in 4-on-5 save percentage, and yet more when combining the two numbers. Also, overall save percentage predicts next year’s overall save percentage slightly better than even-strength save percentage.
all NHL goaltenders do not perform equally. However, the amount of year-to-year variance due to luck is greater than the spread among NHL goaltenders.
Penalty-killing save percentage is a skill, correlated to even-strength save percentage, but one that can hardly be observed. Most of the observed “skill” from stopping shots on the penalty kill comes from the quality of the shots.
USING EV ROAD SV% TO MEASURE GOALIE TALENT
The takeaway here is that if you want to estimate a goaltender’s true talent, you may as well just look at his even-strength road save percentage.
REPLACEMENT LEVEL GOALTENDING
Replacement-level save percentage is approximately 907.8.
The bottom line: goaltenders drive something like 8-10% of winning in the NHL. You could probably even come up with a system that said they were worth 1/6 of all wins. But significantly more than that, say 27%? Not a chance.
WHAT TO EXPECT – REPLACEMENT LEVEL
Replacement level goaltending sv% is .905 and lower
SINGLE GAME SV%
you need to be capable of a very high Sv% to end up playing regularly in the NHL, so the netminders we care about don’t differ a lot in Sv% (i.e., how much better is a 0.915 goalie compared to a 0.912 goalie?).
Long story short: below about 0.825, win probability hovers below 10%; above 0.825, it increases monotonically and steadily until it peaks at 97.6% when the goalie pitches a shutout
single-game Sv% is frequently pretty far from a goalie’s average.
The “Quality Appearances” percentage suggests how tough it is to be an elite NHL goaltender. Only 5 goalies have given their teams a win probability over 50% in more than half their starts;
how stable these save percentage distributions are
Short answer: they’re reasonably stable,
the margin separating NHL goalies in terms of Sv% is pretty thin, so even randomly-generated distributions of Sv% aren’t going to vary that much.
GOALIE PERFORMANCE & SV% CORRELATION
A goaltender has very limited control on the amount of shots they face, but they do have a relatively greater control in how many they stop.
Save percentage is highly repeatable and predictive,
In time, a goaltender’s save percentage stabilizes and the larger sample spacing can be used to make probabilistic predictions of future outcomes
At 1500 shots against you can say with a pretty high confidence level that a 0.925 EVSV% (or lower) goaltender is performing near or at their skill level.
Essentially the average high-paid goaltender was about as efficient at stopping the puck as the average league minimum goaltender.
THE STATE OF SV%
A goaltenders sv% impacts the teams winning percentage, and sv% is the stat that goalies have the most control over.
SV% Win%
<0.885 0.246
0.885 – 0.889 0.503
0.900 – 0.912 0.536
>0.912 0.776
A team wins by out scoring their opponent, which can be accomplished by both increasing goals for and decreasing goals against.
There’s only two possible outcomes: either goaltenders have a very small impact on winning from the variables above or goaltenders impact the game by blocking more shots per than their peers.
a goaltender pushes the needle far more than their team over the long run.
There is not much information added in the long term by adjusting for shot location/quality.
Regular save percentage accounts for just under 90% of the variation we see in the adjusted numbers. How much of that remaining 10% is shot quality factors being weeded out remains to be seen.
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