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Advanced Stats Thread

If you're going to play around with them, I'd suggest using "touching or within the circles" as a dividing line.
 
zeke said:
It's true. We have to realize there's literally no sample size big enough for them to ever consider non-corsi/fenwick success as legit.
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I'm wondering how many actual statisticians are among them, because it's my laymen's understanding that any individual statistic that shows less than a 90% correlation with real world results is pretty much considered entirely invalid across most disciplines.

I could be wrong, but that's the threshold I've heard quoted before.
 
zeke said:
If you're going to play around with them, I'd suggest using "touching or within the circles" as a dividing line.
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Yeah, I was thinking of dividing the slot a few different ways, separating premium area point shots from the corners, etc.
 
MindzEye said:
I'm wondering how many actual statisticians are among them, because it's my laymen's understanding that any individual statistic that shows less than a 90% correlation with real world results is pretty much considered entirely invalid across most disciplines.

I could be wrong, but that's the threshold I've heard quoted before.
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I'm not sure the exact numbers but I think once a single stat can get ~60% correlation that's pretty good. But I could be wrong on that too.
 
zeke said:
I'm not sure the exact numbers but I think once a single stat can get ~60% correlation that's pretty good. But I could be wrong on that too.
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Oh, 55% is pretty good. It's just not "pretty good" enough to draw concrete conclusions imo, which is exactly what the analytics community seems to have done.

I kind of taking the Fontana meme from Anchorman and applying it to his sex panther quote. It works 55% of the time, every time.
 
The thing is, I'm still thinking that there's a bit of conflating of correlation with causation going on with these numbers right now.

Basically, I'd be willing to bet that in the vast majority of cases, a team's Corsi/Fenwick numbers would correlate quite strongly with other methods of projection - i.e. player-by-player PPG and SV% projections. So in most cases, I'd bet that when Corsi/fenwick sees an over or underachievement, then the individual projections would see that same over or underachievment (i.e you'd be able to spot clear unsustainable outlier PPG and SV% performances from career norms or reasonable expectaions).

What I'd be more interested in looking at is the subset of teams in which the Corsi/Fenwick numbers strongly disagree with the individual projections numbers, like this leafs team. I'd wager there aren't that many teams that have been in the Leafs situation - where their performance in the standings is 100% justified by their individual career track records, but completely unjustified by the Corsi/Fenwick numbers. Basically, the subset of teams where the two methods of team evaluation contradict each other this strongly. And I'd like to see which method turns out to be more relevant amongst that subset of teams.
 
Okay...just had a chance to dig through the shot charts from this season and had a few things to share. Basically what I did was took a big rectangle from the outside of the faceoff dots in, from the goal line to the top of the circles. Then tapered it in slightly from the bottom of the circles to the goal line so , basically making a ridiculous looking hexagon.

- First observation...other than the 2 EN goals (Bolland & McClement), every single Leafs goal this season has been scored from that area. All of them, from the most dangerous area of the ice

- Only 6 goals against have come from outside of this zone

- The only win in which the Leafs were "badly" outshot within this zone was the win against Philly when Bernier was superhuman. We were outshot 8-17 from within that high leverage zone in that game. In no other win were the Leafs outshot within this zone by more than 4 shots. In their 4 losses, the Leafs were outshot by a spread of 8 in 2 of the 4 games lost.

- Overall the Leafs the average 15.5 shots from within that area, and give up 16.9

- In Leaf wins the shot spread within that area was 15.6/16.0, in losses it was 15.25/18.75

- 58% of Leafs shots for, were produced in this zone. 48% of shots against originated in this zone.
 
Shot Chart.jpg


I tried to give a little bit of intelligent leeway to both sides, if a shot was borderline from a poor scoring angle I didn't count it, borderline from the high slot though, I did, etc.
 
The more stunning takeaway for me so far is just how many goals, and such a high shooting percentage is scored on shot from that area. If I was an NHL coach I'd be telling my teams to not bother firing from elsewhere either, not in an attempt to score anyway. If it's not an easy shot to tip from outside of that area, it's not really worth the effort.
 
The good news is that the Maple Leafs becoming the star attraction of Advanced Stats analysis has led to some very astute hockey people starting to lend it serious consideration.....and serious counterarguments. The statsboys aren't being left alone in their self-confirming bubble anymore.

par exemple:

http://canuckscorner.com/tombenjamin/2013/10/26/the-leafs-and-the-numbers/

The Leafs and the Numbers

As most readers know, I am more than a little sceptical about the usefulness of hockey statistics, but I’m always willing to take another look at the subject. The most interesting team in the league for those who put a lot of stock in the numbers is probably the Toronto Maple Leafs. The data guys were all pessimistic about the Leafs before the season and they continue to be pessimistic about them now despite their good start.
The biggest single problem that I have with the analytics is the narrative that has emerged to support them. I don’t think that narrative describes hockey. It goes something like this: “Attempted shots – shots, missed shots and opponent’s blocked shots – measure puck possession and the key to winning is puck possession.”

Toronto’s “puck possession” numbers are awful – they are outshot too often and by too much. The assumption is that they have been blessed with an inordinate share of puck luck. Therefore they aren’t likely to keep winning. The argument is not entirely without merit. There is a correlation between shot differential and winning percentage (although it is not particularly powerful and it is not clear how meaningful it is.) Over the course of a season good teams tend to outshoot their opponents and bad ones tend to get outshot.

That said, I don’t think hockey is a puck possession game and in any case I don’t think attempted shots measure puck possession. Teams have essentially the same number of possessions per game, and I doubt if there is much difference in actual possession time. Losers might actually have the puck more!

(I think the key is speed and puck movement. The team that moves the puck the most quickly is the team that gets the most and best chances. There are two separate factors at work in a hockey game. First, there is the team’s ability to control the play – making sure the puck moves slowly toward their own net and moves quickly towards the opponent’s net. That’s about denying open ice to the opponents and creating open ice for the good guys.

A Taylor Hall quality player – I think he is probably the best player in the West – obviously helps a team accomplish those things, but he is still only one skater out of five. Where Hall really makes a difference is when the Oilers do manage to create some ice. That is the second factor. Does the team have finishing ability? When the team gives Hall the puck and open ice, he’s usually going to do something good with it and create a scoring chance. But when the Oilers as a group do not slow down the opponents or find a way to move the puck quickly, their stars become non-factors.)

While “puck possession” numbers do correlate with winning at a league level, there is no apparent link at the game level. Good teams tend to outshoot their opponents, but teams – good and bad – actually do better in games when they are outshot.

The Leafs? In the past three years plus 11 games, their record when they outshoot opponents is 31-44-10. When they are outshot, they are 74-50-15. I understand the qualms data analysts have with the Leafs, but “They get outshot too often” isn’t a particularly compelling argument when you look at numbers like that. When they outshoot opponents the Leafs play like a 69 point a year team. When they are outshot, they are a playoff team with 95 points.

To my eye the Leafs are pretty good without the puck, they do pretty well generating speed through the neutral zone and they certainly have finishing ability. I expect their team shooting percentage to fall somewhat as the season goes on and I don’t think they are a team good enough to get 105 points – their current pace – but I do think they will fight for a playoff spot all year long.

Even if their puck possession numbers suck.
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The Leafs? In the past three years plus 11 games, their record when they outshoot opponents is 31-44-10. When they are outshot, they are 74-50-15. I understand the qualms data analysts have with the Leafs, but “They get outshot too often” isn’t a particularly compelling argument when you look at numbers like that. When they outshoot opponents the Leafs play like a 69 point a year team. When they are outshot, they are a playoff team with 95 points.

Didn't occur to me to go back that far with the numbers but that's awesome - that's what I've been keeping track of all year so far. Why are we a shit team when we outshoot/outpossess our opponents?
 
because we're usually down early in those games, I would guess.

and "first goal of the game" has a much higher correlation with winning than any other stat that I know of.
 
I always see them use actual timed ball possesion in most every game.

Of course, Italy has always loved making a mockery of that stat, too.
 
zeke said:
because we're usually down early in those games, I would guess.

and "first goal of the game" has a much higher correlation with winning than any other stat that I know of.
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I just don't get how that doesn't harm their whole argument though about sustainability though. That's 3+ seasons of winning while being outpossessed. Although he's just using straight up shots there not Fenwick 5 on 5.
 
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