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Advanced Stats Thread

JaysCyYoung said:
The Sharks might be the worst-drafting team in the NHL...
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The Oilers are actually much worse. Having lots of high draft picks and the easiest roster in the NHL to crack obscures that a bit. I'd have Calgary as worse than them also. Or Vancouver. Let's face it. Western Canadians don't know shit about running a hockey team.
 
Oilers have done alright (just before all the top picks) ... Eberle and Cogliano .. both late first rounders.

Sharks seem horrible lately.... but 2005 they got Setoguchi and Vlasic and Couture in 2007

Flames have been just brutal.... though I love Baertschi.
 
Look out for a stat called WOWY. Could eventually replace Corsi as the go to metric. It's being used in some NBA circles as well.

'With or Without You' is a style of analysis used to determine which players benefit the most from their linemates and which players are driving play.
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This guy argues for it and against corsi:






Accounting for Teammates Part 1: Corsi Rel and WOWY

The quality of teammates influences almost every stat in all major sports. This is particularly true of the base stats we tend to use, such as on-ice Corsi or Fenwick rate, because they don't just take something a player has done (score a goal) but also include what his teammates did while he was on the ice. The reason we opt for on-ice stats instead of individual is simple - on-ice stats allow us to measure, albeit noisily, all the contributions a player makes to the thing you are measuring.

How often do you hear an announcer say "that kind of play doesn't show up on the stat sheet, but was very important"? If you're measuring on-ice stats instead of individual stats, and you have a large enough sample, those small plays will show up. The trick is accounting for teammate quality, or at the very least taking it into consideration.


Challenges

The first thing one should recognize is that it's often difficult or even impossible to separate out guys that spend the majority of their time together. The Sedins are an obvious example, but it is very common for a top defense pairing to stick together most of a season and somewhat common for pairs or even entire lines of forwards to play the vast majority of their time together.

It all comes down to sample size. With apologies to Nashville fans in mourning, consider Shea Weber and Ryan Suter last season. Going by hockey analysis, at 5-on-5 they spent 1,293 minutes together, Suter played just under 213 minutes without Weber and Weber played almost 195 minutes without Suter. So they each played roughly 3 games' worth of time apart. With a sample size that small, we can't say much of anything.

Any team can look good or terrible over a three-game stretch. Last year Weber did substantially better when they were apart, but to figure out if one was driving play more than the other you would need several seasons' worth of data and even then it's just going to be a rough idea because those two spent so much of their time together.


A First Attempt - Relative Corsi

The most well known and, unfortunately, most widely used method of dealing with teammates is relative Corsi (Corsi Rel). To calculate relative Corsi, you simply take the possession rate when the player is on the ice and subtract off the possession rate when he is off the ice. The idea, broadly speaking, is that if a player is helping his team then, they will be better off with him on the ice than off. That's a fine idea but I have to say I'm not a fan of this metric at all. I'd love for someone to defend it in the comments because it puzzles me that it is ubiquitous given its major flaws. My intuition is that zone-start adjusted Corsi and maybe even just raw Corsi are better metrics than Corsi Rel.

Fellow Driving Play and NHLnumbers blogger Brent Morris provided a nice article of criticisms. In fairness, one could argue that a lot of the problems are down to misuse. Corsi Rel doesn't really adjust for teammates so much as say how your line/pairing does compare to the others on your team. The adjustment, subtracting off the team's Corsi when you are off the ice, puts most of the weight on the guys the player in question never plays with. If you are a first-pairing defensemen, it's mostly going to be determined by how well the second and third pairings go.

What we'd like to do is see how much credit we should give a player versus the teammates he plays with, and Corsi Rel does that very poorly.


A Step Up - WOWY

WOWY, an acronym of "with or without you", is a pretty substantial improvement. In the basic version, one compares how each teammate does with a player on the ice to his results without that player. The idea is the same - if you are good, you will make your teammates better. If a guy is improving his line/pairing then the other player(s) will be better with him than without him.

WOWY adjusts for teammates (or teammate at least) by holding them constant. If you look at Crosby's performance with and without Pascal Dupuis, Crosby will appear on each side of that. This is a big improvement on Corsi Rel because if Dupuis spends a lot of time with Crosby, Sid would mostly be in the Corsi On part which would elevate Dupuis's numbers.

One big issue with WOWY is that you can still get a dragged-along-by-teammate effect if you aren't careful. If you look at a Vancouver defenseman's Corsi with and without Alex Burrows he will be drastically better with Burrows on the ice. Burrows may be a good possession player but as pointed out above it's tough to say since he spent so much time with the Sedins; so it seems likely that a healthy share of the credit there should go to Henrik and Daniel. For this reason it is generally best to run WOWY numbers against teammates on the same color line - forwards with forwards and defensemen with defensemen. If you run it on a defenseman for a forward or vice-versa the results will be very similar to Corsi Rel and carry all those problems.

It's beyond the scope of this article, but you can do more fancy versions of WOWY by looking at combinations of players. For example, you could look at Pittsburgh's Corsi rate with and without Dupuis when both Crosby and Letang were on the ice. This allows you to take into account the quality of both forward and defensemen. The downside is that you are going to shrink the sample sizes pretty dramatically so you might have to go to multiple seasons, which can cause its own problems.


Final Thoughts

Something to keep in mind with both of these is that you are always doing a comparison - in the case of Corsi Rel you are comparing a player, and his line, to the performance of his teammates when he is off the ice. If you have two equally skilled fourth liners, the one playing for Detroit or St. Louis will have a much worse Corsi Rel than the one playing in Minnesota or Nashville because the players in the comparison group are much better.

WOWY is the same way - Crosby's results without Dupuis depend on who tends to slot in when Dupuis is injured or shifted to another line. Keep in mind that you are always comparing a player's performance to some specific group of teammates. This is important if his team is very strong or weak at the same position or if you are using one of these to compare players on different teams.

In the next installment, I will look at a couple methods that get around this by assessing everyone at once - regression and Vic Ferrari's King Value.
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http://nhlnumbers.com/2012/7/18/accounting-for-teammates-part-1-corsi-rel-and-wowy
 
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One thing I've noticed in looking at Corsi is that it seems to ring much truer for dmen than it does forwards.

and it would make sense that adding a third linemate and an extra line makes it many times harder to isolate an individual's performance.
 
Forwards are tougher because one great forward (or bad forward) can drive his linemates numbers either up or down.

With Corsi -- it's probably best applied comparing line vs line, d pair vs d pair as opposed to player vs player.

If you compared Phaneuf's numbers with Hozler and without Holzer, the numbers would be pretty extreme, I'd say.
 
If an advanced stat comes back and says negative things about Jay McClement's defensive impact, I think that says negative things about the validity of the statistic rather than negative things about McClement's defensive impact.
 
I think McClement was highly overrated, like so many 4th liners in this market always are.

McClement was a decent 4th line C and good PKer, nothing more. (and remember, these advanced stats are all about 5 on 5 play, not special teams).

In fact, his surprising 3rd-line quality offensive contributions impressed me more than his defense, IMO.
 
They just keep making the same mistake and confusing possession with defense. Possession is possession. It might be a factor in defensive effectiveness, but it does not encompass all that is defense. If it were a venn diagram possession and defense might overlap, but they'd still be separate circles.

Of course McClement's possession numbers stink. He has no talent.

But given the fact that he doesn't have the puck very much, his efficiency and defensive production stats are great. The guy just flat out plays hockey the right way. its pretty hard not to appreciate it.
 
zeke said:
I think McClement was highly overrated, like so many 4th liners in this market always are.

McClement was a decent 4th line C and good PKer, nothing more. (and remember, these advanced stats are all about 5 on 5 play, not special teams).

In fact, his surprising 3rd-line quality offensive contributions impressed me more than his defense, IMO.
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Stop drinking so much during Leaf games, zeke. ;)

I disagree. Defensively Leafs would give up many more goals if we didn't have McClement in the lineup. His positioning and work rate isn't matched even by a guy like Kuly(although it's close). As for his possession numbers...Not sure what they are but he's actually quite good at that part as well.He just wasn't used much(in that sense) and if you look at who he had to play with most times(only so much 1 guy can do) he was good enough.
 
McClement started 27% of his shifts in the Leafs zone. He only finished 41% of his shifts in the offensive zone. His possession numbers are near the bottom of the team. What all that says is he spent a shit load of time in his own end.

But his GAon/60, and onice save%, were the best of all Leafs regular forwards and he had the 3rd highest Corsi Rel QOC on the team. So he played tough minutes, spent a shit load of time in his own end, but flat out less goals were scored when he was on the ice than any other regularly playing forward on the team.

Nothing about that says bad defense.
 
The whole point of hockey is to outscore your opponent. And you can't do that without the puck.

So, if you have a player, for whatever reasons, is always playing without the puck, he has a negative impact on your ability to win.

I don't like to isolate offense and defense -- because they are directly linked.

McClement either has a positive, negative or neutral impact 5 on 5.
 
leafman101 said:
McClement started 27% of his shifts in the Leafs zone. He only finished 41% of his shifts in the offensive zone. His possession numbers are near the bottom of the team. What all that says is he spent a shit load of time in his own end.

But his GAon/60, and onice save%, were the best of all Leafs regular forwards and he had the 3rd highest Corsi Rel QOC on the team. So he played tough minutes, spent a shit load of time in his own end, but flat out less goals were scored when he was on the ice than any other regularly playing forward on the team.

Nothing about that says bad defense.
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And the Leafs allowed the 2nd most shots on goal when he was on the ice.

Good thing they had a good goalie behind him to stop all those shots.
 
The Leafs got killed 5 on 5 when they used their bottom 6 forwards lines. Their top 6 weren't too bad from a possession standpoint. But the bottom 6ers played way too much without the puck, and that has a lot to do with the fact guys like Orr, McClaren, Hamilton, McClement, etc just aren't talented enough even in comparison to other teams bottom line players.

Additions of Clarkson, Bolland should help, I think.
 
They didn't get killed though when McClement was on the ice. They gave up less goals than when anyone else was one the ice.

These need to generalize everything in hockey down to one stat is beyond nuts, and obviously doesn't work. An honest belief that everything in hockey can be narrowed down to corsi just flat out doesn't comport with the game of hockey IMO.
 
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PlayerToBeNamedLater said:
And the Leafs allowed the 2nd most shots on goal when he was on the ice.

Good thing they had a good goalie behind him to stop all those shots.
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They had a good goalie to play behind everyone and stop all the shots. Still gave up less goals when McClement was on the ice than anyone else.

But for some moronic reason that had absolutely nothing to do with McClement right?
 
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leafman101 said:
They had a good goalie to play behind everyone and stop all the shots. Still gave up less goals when McClement was on the ice than anyone else.

But for some moronic reason that had absolutely nothing to do with McClement right?
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No, I don't think McClement gets credit for the goalie making more saves when he's on the ice.
 
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