The Day David Staples Killed Corsi Because…Taylor Hall

File:Taylor Hall.JPG

Photo by Alexiaxx, via Wikimedia Commons

I’ve been following the story of Taylor Hall as the season progresses, particularly through Tyler Dellow’s attempts to un-vex the vexing year Hall is having (Parts IIIIIIIV). In Tyler’s second part, he notes three differences between this year and last year: fewer zone entries with a carry, poorer retrieval of dump-ins, and a lower shots-per-carry total. The latter, Tyler notes, is likely symptomatic of a larger emphasis on dumping-in, wherein a player carries to just inside the blue line before dumping. He quotes Dallas Eakins as suggesting that Hall, in-particular, seems to take this dumping-in approach to heart. I’d add that there’s a possibility that this is abbreviating potential offensive zone possession time, as overall Hall and the other Edmonton Oilers have dropped from nearly 50 seconds per shift to 47 seconds. Further to that point, Tyler noticed in the fourth part that the Oilers have seemed to adopt a tip-in dump-in, wherein the player in the neutral zone either redirects or chips, while standing in place, the puck into the offensive zone. Just based on the video evidence Tyler provided, this looks like an extraordinarily passive approach to the dump, equivalent to dumping and getting off the ice. In that latter scenario, you are unequivocally giving up possession. In the tip-in approach, you take your active close player and leave them in-place, in favor of a later-to-the-game forechecker. It would seem to me that you’d benefit from an active dump-and-chase forechecker.

There are a couple of others irons you can put in the fire, including variance of CF% (a 5% swing is not unheard-of, particularly moving from a 48 to a 56-game sample), potential fatigue from increased playing time (he’s taken on some penalty kill minutes and more even-strength minutes this year), and the swapping out of Ales Hemsky as a linemate (for Sam Gagner). The tougher competition, for me, is essentially washed out by a bump up in offensive zone starts. I don’t see evidence of recording bias, either. I suspect a couple potential, additional things: 1) the drop-off is right there with the Ovechkin-Dale Hunter drop-off, so there might be some player vs. system aggravation, and 2) some fatigue issues related to the early-season knee injury. Injuries aren’t just about pain, they can also compromise strength and endurance. A guy like him, who has had injury issues in the past, does not want the “soft” label (you’ve seen what that’s done to Hemsky’s time in Edmonton), and might not want to admit it to the media or himself.

Up to this point, you’ve seen Dellow’s and my own introspection into what appears to be a poor possession season from Taylor Hall. Enter David Staples.

Immediately, the modus operandi is clear: if Staples had to choose between a measure and a man, he would pick the man. Good for him. Now tired of real people, and their work, Staples then builds up a straw man that sings Corsiatto (in “What I’ve Often Read”), who has decided that the only measure of Taylor Hall is CF%. This fool has never considered the possibility that Taylor Hall is not responsible for every shot-for or against that occurs while he is on the ice. Me personally, and most of the rest of the stats folk I read, would grant him that yes, Hall is not responsible for all of those.

Now Staples takes us to the research, which is admittedly pretty telling and interesting. He notes that Hall was on the ice for 639 shots-for and 828 shots-against at 5v5. Staples postulates that theoretically Hall is, in a vacuum, 20% responsible for the play in his time on-ice (Staples cites for the information, despite the fact that the math is Hall is 1 of 5 Oilers skaters when he’s on the ice). This is true at the TOI level, but Staples somehow determines that Hall is probably not even 20% responsible for shots-for, or 20% for shots-against, based on absolutely nothing except David Staples. He finishes that paragraph with a flourish:

“He’s been awarded a number of false positives and all kinds of false negatives on plays where he had no real impact on shot-at net, or maybe even was doing his job well but still got a negative because someone else screwed up. Corsi% is utterly riddled with false positives and false negatives. It’s so noisy that it can’t tell us much about individual players.”

Well, first off, how you can ever conclude with that kind of confidence that Taylor Hall is somehow less responsible for on-ice play than anyone else needs a bit more logic, or data, or logical data. Staples’ creation of a world where Hall, in an even-strength discrepancy of less 189 shots, is somehow a positive 200 shots is, to use a technical term, bonkers. Unless there’s a net I’m not aware of by the penalty boxes, there is no way any player could be that disconnected from their on-ice play. Think of it this way: if Taylor Hall is so far from the defensive zone he cannot be directly attributable for giving up a shot, he is still, in fact, accountable for not being in the defensive zone. And vice versa, the decreased possession and resulting 4v5 shot rate in the offensive zone.

Even before this Staples uses WOWY analysis, an occasionally sketchy (sample-wise) endeavor unless you can get a consensus signal. And lo-and-behold, Staples gets it. The data staring him in the face, he uses that chart to conclude that all those players share the blame, rather than using the WOWY to note that almost all of those players have a worse CF% with Hall than without. And since you are taking away one of the better players, a 1st-liner, on the Oilers in that WOWY, you cannot assume that Nugent-Hopkins, or Eberle, or any of the others are playing with better teammates. That’s a pretty damning signal.

But Staples decides to diverge into an exercise in his own statistics, revolving around goal-analysis that ignores what might actually drive scoring (possession, aka what we were just looking at). Here, the signal is clear for him: forwards are responsible for more goals-for than defensemen and goalies, and fewer goals-against in the same comparison. Which, if he’s quantifying responsibility for goals the way I think he is, would ring true for every other hockey team on Earth. In this measure, Hall is actually contributing more than he’s giving up, therefore he’s a positive player and Corsi’s wrong, inherently flawed.

Of course, tying direct contributions to goals or shots is going to lead to this kind of thinking, because by proximity forwards are more invested in shots and goals and defensemen more invested in shots and goals-against. But, as Mike Babcock recently pointed out in Canada’s march to gold, offensive possession is the goal, and does the defense for you. It keeps the puck in your hands, and possession period puts you almost entirely out of danger in any zone.

Staples ends his piece with the utmost conflation, putting analysis of goals plus-minus on-par with Corsi measures, essentially ignoring the wealth of data and results that suggest that this is way off the mark. The reasons for Taylor Hall’s regression this year are many, and it deserves deep research into the data; but shallow fluff designed to push some agenda in a fight no one’s fighting anymore shows just what kind of mudslinging still goes on in the name of “hockey analysis.”

One thought on “The Day David Staples Killed Corsi Because…Taylor Hall

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