# NHL goalies better vs high shot volumes

Discussion in 'By The Numbers' started by Mathletic, Mar 26, 2014.

1. ### Doctor NoRegistered User

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This is a combination of all NHL data (regular season and postseason), 1970 through last night, grouped by the number of shots faced per game.

I included "expected saves" based upon the season, opponent, and (where applicable) the postseason scoring environment. Given that there's almost 50 seasons worth of data, and that actual save percentages fluctuated wildly over that time, I'd focus on the relationship between actual save percentage and expected save percentage.

This includes all games, even where a goalie was pulled or was a replacement - if a goaltender faced 10 shots in 20 minutes of play, then they are in the "30" category.

My data currently does not have scoring by period, which would help to address the impact of score effects. I'm hoping to add that in at some point.

2. ### Doctor NoRegistered User

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The next table(s) would be one really wide table - really wide table - if I put it all into one. So if you have a goaltender you're interested in, I would just CTRL-F each of the tables I'm about to present.

These are the same statistics as the above table, by goaltender (REGULAR SEASON only), for those goaltenders meeting a 1000+ minutes/situation threshold.

3. ### Doctor NoRegistered User

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Goaltenders in games where they faced 22.5 shots/game or fewer:

4. ### Doctor NoRegistered User

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Goaltenders in games where they face 22.5 to 27.5 shots per game:

5. ### Doctor NoRegistered User

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Goaltenders in games where they face 27.5 to 32.5 shots per game:

6. ### Doctor NoRegistered User

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Goaltenders in games where they face 32.5 to 37.5 shots per game:

7. ### Doctor NoRegistered User

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Goaltenders in games where they face 37.5 shots per game or more:

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^^The problem with tables like that is that you're doing goalie to goalie comparisons. The idea is to compare each goalie to himself.

Example
Hasek in 30+ shot games: .933
Hasek in 29- shot games: .916

9. ### Mike FarkasGrace Personified

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So, Doc, this reads to me like it knocks save pct. down a peg, no? If something is correlated pretty highly to sheer volume, that doesn't seem indicative of individual play. You make any interpretation from this?

10. ### Doctor NoRegistered User

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Yes, you're consistently beating the drum that your way is the only way to do it, that it's flawless, and that anything else should be ignored.

Anyhow, I put those tables up there for your benefit. Go ahead and use them - I wasn't going to post 800 tables, one for each goalie.

11. ### Doctor NoRegistered User

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I wouldn't say that it knocks save percentage down a peg - I'd argue that people should have already had it down on whatever level it should have been.

Score effects are known, and shot counting biases are known, and we know that not all shots are created equal in general. Does it even out in the end? Probably not. Do we have much better from days of yore? Probably not.

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If I gave this impression, I certainly apologize. But wouldn't it be wrong to deny that every goalie has a lower cumulative SV% in the lower shot volume games? I just have not found a single goalie who has a higher SV% in his "29 or fewer" shot games than he does in his "30 or more" shot games. And I've looked at several goalies both retired and active.

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I do think that when a goalie only has say a .915 SV% and a low GAA say 2.05 or something, I do think people should check to see where his team ranks defensively in shots allowed.

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Here is the "29 or fewer" vs "30 or more" splits for the current Eastern Conference starting goalies. This is only including the games where the goalie played at least 55 minutes, and also does not include games played from this season.

WESTERN CONFERENCE

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My bet from for sure is that -- certain teams -- drive this stat.

Anytime a Manny Fernandez, Craig Andersson or Boborovsky or someone like that have a monster season (in terms of stats?), its always a synergy between the goalie and the team. I have like never seen a team isn't in synch have a goalie that stands on his head for a full season. While it always -- and at least if you look back the last 20 years -- have been quite common with teams that realize that they can win games one way and one way only, and that is to grind it out night in and night out. Giving up the momentum battle, and digging down instead.

I have always been a bit frustrated with the Vezina voting, since the one-hit-wonders always get the most votes based on a few decimals in one stat. And these teams are always behind them...

16. ### authenticRegistered User

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This is something I've figured for a long time and have occasionally read some stats that I thought supported it, and now thoroughly reading through this thread and analyzing the various stats posted it is so blatantly obvious that higher save percentages are almost entirely correlated with more shots faced. This has actually made me question my previous stance on Roy being clearly better than Brodeur.

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It's not the raw number of shots that affects it, it's the ratio of high shot games to low shot games that's important.

Speaking of Brodeur, he faced 30 shots in only 304 of his career 1266 games (24%). This compared to Hasek who faced 30 shots in 314 of his career 735 games (43%).

Brodeur has a career SV% of .912, aka 91.2% and Hasek has a career SV% of .922, aka 92.2%.

18. ### AfroThunder396[citation needed]

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Doc, do you still have this data? It looks like it was lost when we switched boards. I was hoping I could cite it.

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19. ### Doctor NoRegistered User

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I'll see what I can find!

(The 99% sure answer is that yes, the raw data is on my hard drive somewhere, and it's a question of whether or not I can find it).

In the meantime, I've started looking at shots/period effects (the hypothesis being that when a team is down in a game, they start throwing everything at the net, which results in high-shot high-SVPCT games for the winner) but that will have to be another post.

20. ### Doctor NoRegistered User

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Ooo - I actually labeled the Excel file "Shot Volume Analysis 2016-11-23" and my posts were 11/23/2016, so we'll call that a freebie.

This is data from 1970-71 through November 22, 2016 (so the same data as originally presented), and wouldn't have any corrections I've made to the underlying data since then.

EDIT: Going to have to figure out another way to do this, since the formatting I put in the Excel file was specific to the old website (and pasting as images is both less useful and super large).

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There is definitely an inflating and deflating effect depending on how many low shot volume or high shot volume games a goalie plays in. By no means am I saying that if one goalie averages 30 shots against and another goalie averaged 25 shots against that the goalie who averaged 30 shots is gonna have the higher SV%. There is a difference between facing 1800 shots in 60 games as opposed to facing 1800 shots in 72 games. 1800 shots in 72 games would be more difficult to maintain a higher SV%, because there's much less margin for error.

For example, Marty Turco in 2003 as opposed to Tim Thomas in 2009.

Turco in 03
GP: 55
SV%: .932

Thomas in 09
GP: 54
SV%: .933

They're pretty much identical. The difference though is in the shots per game.

Turco in 03
SA/G: 24.7

Thomas in 09
SA/G: 31.4

As a result, there was a fairly significant gap between their GAA's.

Turco in 03
GAA: 1.73

Thomas in 09
GAA: 2.10

As you can see, Turco would have had a much more difficult time maintaining his .932 if he played say 10-15 more games. If he allowed 2 or more goals, he was actually hurting his SV%. Thomas could allow 2 goals more frequently and still maintain his .933.

Another layer to this is that when you split the games up into shot bins, the GAA goes up as the shots go up. Ironically enough, so does the SV%. You allow more goals when you face more shots, yet your SV% will also increase.

Here is some data from 13/14 through 17/18 ONLY INCLUDING GAMES WHERE THE GOALIE PLAYED 50 MINUTES OR MORE

19 or fewer shot games
SV%: .891
GAA: 1.89

20-29 shot games
SV%: .908
GAA: 2.33

30-39 shot games
SV%: .925
GAA: 2.53

40 or more shot games
SV%: .937
GAA: 2.69

Final thing I want to make abundantly clear. It's NOT the shot totals that make the difference. What ultimately affects the SV% is the number of games where the goalie sees a high / low number of shots. IE the RATIO of high shot volume to low shot volume games is what you want to look at.

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22. ### Bear of Bad NewsHFBoards Escape Goat

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Given the intense vitriol in the other (now closed, and not by me) thread, this is going to be on an exceptionally short leash.

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24. ### Doctor NoRegistered User

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What does this all mean?
It means that shot volume is not a good explanation for a goalie’s save percentage, either in a positive or a negative way. Seeing high volumes at the game level tends to inflate save percentage a small amount, especially at the extremes, without shedding any additional light on actual performance. If your goalie is seeing a lot of shots in a specific game, it should be expected that their save percentage will be inflated.

As a goalie plays more games, even the slight tendency towards inflation weakens and disappears for all practical purposes. At the season level, the range of save percentage values is so large and the number of data points is so small that the distinction between a high shot season and a low shot season is largely unimportant for deciding what save percentage we expect of a goaltender.

In other words, looking at shot volume doesn’t get us very much closer to understanding why a goalie posted the numbers he did, but it does have an effect on how save percentage looks. It’s important information about the statistic because these mathematical realities limit how much information we can actually glean from save percentage.

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I want @Hockey Outsider to see this too.

Exactly what I've been saying. It's why the per 60 stats don't work. Every game is different and each game needs to be kept separate without overlapping into another game.

If you take all of the singular games separated by shot bin and accumulate them WITHOUT combining shot bins, you will realize that the higher shot total games will have a higher SV than the lower shot volume games.

It's all I'm trying to show. All of it is is a different kind of split like home/away.

Correct. You don't want to use overall shots as a way to predict SV%.

More shots =/= higher SV%
Higher SA per GM =/= higher SV%

A goalie who averages 30 shots a game can easily have a lower SV% than a goalie who averages 25 shots a game.

All of these points in this article I've addressed. This article has very much expressed the same opinion I've had this entire time. This is WHY I've been saying that I don't think you guys understood what my point was.

Here's another way of looking at it. If one goalie sees 1800 shots over 70 games and another goalie sees 1800 shots over 60 games, the goalie who played 70 games will have a more difficult time maintaining a high SV% than the goalie who played in 60 games.

It's not the raw shot total that's important. The most important factor is and forever will be the ratio of high shot games to low shot volume games.

It's not hard to understand that 1 goal allowed on 25 shots will be a lower SV% than 1 goal allowed on 30 shots.