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Man Advantages and Success in the Standings

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08-08-2012, 12:50 PM
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Iain Fyffe
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Man Advantages and Success in the Standings

Due to a comment in a recent thread in the History forum, I dug into the correlation between a team's success in the standings and its net man-advantage situations. See my blog post here.

Any thoughts?

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08-08-2012, 01:21 PM
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Czech Your Math
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Quote:
Originally Posted by Iain Fyffe View Post
Due to a comment in a recent thread in the History forum, I dug into the correlation between a team's success in the standings and its net man-advantage situations. See my blog post here.

Any thoughts?
There are two reasons for a positive correlation:

A) the stronger teams should be creating more even strength advantages, which cause more penalties by the opponent, and therefore more net power plays

B) the teams with more net PPs should directly benefit by scoring more net goals and therefore appear stronger

The negative correlations are much more blatant evidence of something unusual at work than the positive correlations are of nothing unusual. You know my view: the NHL wanted to make the weaker teams more competitive, which will keep the fans more interested and generate more revenue. One might term this the "there's no business like show business" theory.

The only reason for a negative correlation which comes to mind is as follows. A stronger team may at times choose to commit a penalty to prevent a likely scoring chance by a much weaker team, knowing that the weaker team will often be much less likely to be able to take advantage on the power play (esp. against a strong team). Given that any team will often commit a penalty to avoid such a likely scoring chance, and that even the best teams don't convert more than ~1/4 of their power plays (and only the very strongest historically achieve that), it doesn't seem like that should be too much of a factor. Combined with the much stronger reasons for a positive correlation, the evidence is overwhelming that the correlation should be positive.

Given the evidence you've already presented, what would be helpful is to see net power plays vs. ES GF/GA ratio or differential. This both removes the direct influence of the power plays themselves and gives a more direct indicator of how strong the team was at ES (and so more directly measures how likely they should be to create ES advantages which necessitate penalties by their opponents).

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08-08-2012, 04:56 PM
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Originally Posted by Czech Your Math View Post
The only reason for a negative correlation which comes to mind is as follows. A stronger team may at times choose to commit a penalty to prevent a likely scoring chance by a much weaker team, knowing that the weaker team will often be much less likely to be able to take advantage on the power play (esp. against a strong team).
I make this very point in the post. I think it's the most likely explanation for the negative correlation, however more work would certainly be needed to confirm that.

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08-08-2012, 05:54 PM
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Originally Posted by Iain Fyffe View Post
I make this very point in the post. I think it's the most likely explanation for the negative correlation, however more work would certainly be needed to confirm that.
Sorry, I just looked at your chart and didn't have time to read through your blog at that time.

It's certainly a possible factor, but I would doubt it really explains negative correlations. Perhaps it slightly lessens the expected positive correlation, but there's not even actual evidence of that at this point.

You make a good point about the score effect, but wouldn't the leading team play defense in an effort to avoid the high quality scoring chances which may necessitate penalties? Otherwise, they would be A) giving up more shots (according to what you said), B) giving up the same % of high quality shots, and so a greater number of high quality scoring chances, C) decreasing their own shots and scoring chances. How would this help them protect a lead? I would guess they might decrease their own shots and scoring chances, in exchange for more possession and/or fewer high quality scoring chances for their opponents. This would make sense to me, but then it should not increase the high quality scoring chances for their opponents (which shouldn't increase penalties by the leading team). Also, the leading team, by giving up scoring chances of its own, would be seemingly avoiding penalties which might be committed to create their own offensive advantage, which might negate much or all of any effect that is there from them giving up more shots.

I think the ES GF/GA data vs. new PPs (or NOMS as you term it) would be the most helpful at this points. It's not my highest priority right now, but I may look at it in the future.

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08-16-2012, 02:14 PM
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I looked at this a little further.

From '87 to '89, the correlation between ES goal differential and NOMS was: -57%, -32% and +15%. So the correlation doesn't seem to be due to the direct effect of net NOMS on team performance. If you divide the teams into two groups, the extremes and moderates by ESGD, the difference only becomes more stark. For instance in '87, the extreme 10 (top 5 and bottom 5) had a -77% correlation, while the extreme 6 (top 3 and bottom 3) had a -92% correlation. Meanwhile, the moderate 11 had a +21% correlation and the moderate 15 had a +4% correlation. These are the types of numbers one sees league-wide in '89 (+15%). I also had data from the past 5 seasons, so calculated that and the correlations averaged +11% with a range of 0% to +22% during the 5 years.

It's apparent that the league must have been favoring weaker teams at the expense of better teams. Why and how they suddenly changed within a couple seasons is difficult to say. Perhaps the increase in PPs caused the refs' focus to go from evening things up to calling more penalties in general, but the change is fast and furious. Another factor, suggested by the data, is that as more penalties were called, and called more fairly, teams became more conscious of avoiding penalties against strong PP teams. They could get away with things earlier, because the refs weren't calling so many penalties, particularly against weaker teams. Once this changed, teams' strategies likely also changed.

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