tag:blogger.com,1999:blog-3299311926633621468.post3278795309644893420..comments2024-03-17T01:16:08.920-07:00Comments on Objective NHL: The Repeatability of Special Teams PerformanceJLikenshttp://www.blogger.com/profile/02570453428274983835noreply@blogger.comBlogger14125tag:blogger.com,1999:blog-3299311926633621468.post-23855017344768649112013-05-03T14:20:11.619-07:002013-05-03T14:20:11.619-07:00I didn't know that you used that kind of metho...I didn't know that you used that kind of method to predict the winner and it sounds quite interesting. Host Pay Per Headhttp://www.hostpph.comnoreply@blogger.comtag:blogger.com,1999:blog-3299311926633621468.post-65520846864187884022010-05-04T15:16:09.106-07:002010-05-04T15:16:09.106-07:00Tom:
You're right - the inclusion of home ga...Tom:<br /><br />You're right - the inclusion of home games is going to make each metric appear to be more sustainable than it actually is (aside from powerplay ratio, of course).<br /><br />Initially, I considered looking only at road games, but decided against that because I didn't want to make the sample any smaller than it already was.<br /><br />That said, I think I'll take your suggestion and re-run the experiment for road games only. If nothing else, it'll provide an interesting comparator. <br /><br />BTW, your questions aren't stupid - they raise some legitimate issues that I didn't address in my post.JLikenshttps://www.blogger.com/profile/02570453428274983835noreply@blogger.comtag:blogger.com,1999:blog-3299311926633621468.post-54444494354303706752010-05-04T14:09:39.836-07:002010-05-04T14:09:39.836-07:00Another stupid question (I'm full of them!): a...Another stupid question (I'm full of them!): any idea if arena bias plays in the PP / SH rates? At evens it balances out, but if we have arenas that record fewer shots suddenly we're seeing "repeatable skill". It would affect the percentages too, in the other direction, but there's so much noise there that you wouldn't notice it. <br /><br />It would be interesting if you did only road games. The coefficient would go down, but it might go down more than we think.Tom Awadhttps://www.blogger.com/profile/09368984892070888703noreply@blogger.comtag:blogger.com,1999:blog-3299311926633621468.post-49821768611604798502010-05-04T14:03:13.301-07:002010-05-04T14:03:13.301-07:00Just checking. Excellent analysis, BTW.Just checking. Excellent analysis, BTW.Tom Awadhttps://www.blogger.com/profile/09368984892070888703noreply@blogger.comtag:blogger.com,1999:blog-3299311926633621468.post-14574108553192991582010-05-04T11:20:36.483-07:002010-05-04T11:20:36.483-07:00Tom:
There was no overlap.
If a game was chosen ...Tom:<br /><br />There was no overlap.<br /><br />If a game was chosen in one group, it was not included in the other.JLikenshttps://www.blogger.com/profile/02570453428274983835noreply@blogger.comtag:blogger.com,1999:blog-3299311926633621468.post-89567238943414514562010-05-04T10:09:34.859-07:002010-05-04T10:09:34.859-07:00Stupid question... in your 2 samples of 40 games, ...Stupid question... in your 2 samples of 40 games, can there be any overlap (i.e. games chosen in both samples?). That would skew the results.Tom Awadhttps://www.blogger.com/profile/09368984892070888703noreply@blogger.comtag:blogger.com,1999:blog-3299311926633621468.post-17512667303316803262010-05-02T22:38:33.055-07:002010-05-02T22:38:33.055-07:00Vic:
Good point - the 5-on-3s are a big confound....Vic:<br /><br />Good point - the 5-on-3s are a big confound.<br /><br />Your suggestion about comparing the 4-on-5 SV% of the starter to his backups is a good one.<br /><br />I actually remember doing a similar exercise last year (i.e. looking at the (weighted) correlation between the SV% and his backup within certain seasons). <br /><br />In order to mitigate sample the size issues, I assigned each data point a weighting based on the number of shots faced by the backup. <br /><br />I wasn't able to find much - If I recall correctly, the correlation was about 0.15 for EV and 0.04 on the PK. However, the PK data included 5-on-3s, which, as you said, tends to distort things.<br /><br />I think I'll take your suggestion and repeat the exercise at 4-on-5 only (ideally, with home games excluded as well).JLikenshttps://www.blogger.com/profile/02570453428274983835noreply@blogger.comtag:blogger.com,1999:blog-3299311926633621468.post-31178558997660830942010-05-02T17:59:51.032-07:002010-05-02T17:59:51.032-07:00I think that getting rid of the 5 on 3 PKs would m...I think that getting rid of the 5 on 3 PKs would make a significant difference. There are teams that just never seem to have to kill one off (I don't know if I've ever seen MIN killing a 5 on 3) and teams that always seem to take a whack of penalties while PKing (ANA comes to mind). That's going to make a measurable difference when we're looking at things so closely.<br /><br />Also, shot counter bias is huge here. Corsi and Fenwick provide some remedy for that at EV, but they don't help us on special teams. I think a guy would have to use just road games in order to minize that effect.<br /><br />A quick check for team effects on goalie PK save% would be to look at team 4v5 save% from Gabe's site. Then the same for the No.1 goalie on each team. Then subtract the shots and saves for each goalie from his team's totals. That would be the combined backup goalie shots and saves on the PK.<br /><br />Then see if there are any real effects from starter to backup(s). <br /><br />Makes sense, no?Vic Ferrarihttps://www.blogger.com/profile/16425585921916867277noreply@blogger.comtag:blogger.com,1999:blog-3299311926633621468.post-1148697502979771942010-05-01T19:54:35.369-07:002010-05-01T19:54:35.369-07:00Scott:
You're right - both explanations are p...Scott:<br /><br />You're right - both explanations are possible.<br /><br />I suppose one way to settle the issue would be to compare the PK SV% of goaltenders that changed teams to the PK SV% of goaltenders that remained with the same team. <br /><br />Perhaps that's something that I ought to look at this offseason.JLikenshttps://www.blogger.com/profile/02570453428274983835noreply@blogger.comtag:blogger.com,1999:blog-3299311926633621468.post-72269370265667682342010-05-01T00:00:14.423-07:002010-05-01T00:00:14.423-07:00Thanks for the response.
Why would the stronger...Thanks for the response. <br /><br />Why would the stronger correlation in PK save percentage suggest that the team has a greater effect in that situation? If the percentage of scoring chances per shot is higher on the PK, perhaps that situation is more revealing of goaltender ability. On the other hand, maybe some teams really are better than others to a significant degree at limiting shot quality on the PK. It's an interesting question but I'm not sure I'm fully comfortable with either answer as the right one just yet. Though if I had to guess, I would side with you that the team has a greater effect on the PK than they do at EV.Scott Reynoldshttps://www.blogger.com/profile/05735545121522530577noreply@blogger.comtag:blogger.com,1999:blog-3299311926633621468.post-11862156692859489002010-04-30T13:42:04.651-07:002010-04-30T13:42:04.651-07:00Vic:
Thanks.
It wouldn't have been possible ...Vic:<br /><br />Thanks.<br /><br />It wouldn't have been possible but for your initial post on real effects.<br /><br />It's a great method, and not something that I would have come up with on my own.JLikenshttps://www.blogger.com/profile/02570453428274983835noreply@blogger.comtag:blogger.com,1999:blog-3299311926633621468.post-39326766544025595132010-04-30T13:40:06.611-07:002010-04-30T13:40:06.611-07:00Scott:
Thanks.
You raise a good point about the ...Scott:<br /><br />Thanks.<br /><br />You raise a good point about the sample size that I planned to address in my post, but opted not to in order to keep the post length tolerable.<br /><br />40 games is a fairly small sample, and if you look at the seasonal correlation for the same variables, the relationship is invariably stronger. For example, the seasonal correlation for PP S% at the team level is somewhere on the order of ~0.25. <br /><br />The strength of the PK SV% correlation is interesting, though. If the same exercise is applied to EV SV% with the score tied, the average correlation is about 0.10. The increased correlation observed with PK SV% is not the result of sample size, as the number of shots faced over the course of a season is about the same for both situations (~500 ). <br /><br />As the goaltender exerts influence in both situations, the implication is that team factors have an effect on PK SV%. I believe that Vic made this point a while back, although I can't remember where. <br /><br />Regarding your other question, the data includes all powerplay situations, rather than just 5-on-4. Ideally, I ought to have isolated 5-on-4 situations. However, because I scraped the information from the NHL.com play-by-play feed - which merely identifies whether or not the shot was taken on the powerplay, and not the specific type of man advantage --, I wasn't able to.JLikenshttps://www.blogger.com/profile/02570453428274983835noreply@blogger.comtag:blogger.com,1999:blog-3299311926633621468.post-4742833302937739352010-04-29T22:52:28.413-07:002010-04-29T22:52:28.413-07:00Great stuff again, J.Great stuff again, J.Vic Ferrarihttps://www.blogger.com/profile/16425585921916867277noreply@blogger.comtag:blogger.com,1999:blog-3299311926633621468.post-7903752121176125082010-04-29T20:40:03.122-07:002010-04-29T20:40:03.122-07:00Thanks JLikens! This is great!
The results are a...Thanks JLikens! This is great!<br /><br />The results are about what I'd expect, though PK save percentage looks to be more repeatable than I'd anticipated. I just figured forty games wouldn't usually provide a big enough sample of PK shots to get a look at the real ability of goaltenders.<br /><br />A quick question: Does this data include only 5-on-4 situations or do they also include 6-on-4, 5-on-3 and 4-on-3 chances?Scott Reynoldshttps://www.blogger.com/profile/05735545121522530577noreply@blogger.com