Grabovski's Corsi shows he's excellent at driving the direction of play

After a discussion with Kent Wilson of NHLNumbers.com on the psychology of choosing your fourth line forwards went pretty well, we figured it might be a decent idea to have the occasional back-and-forth in hopes of digging up a few interesting observations. Kent is more of a numbers guy, and my experience comes from playing, so there’s some healthy contrast here.

Below we discussed Corsi, what affects it most, and if it will ever hit the mainstream. If you don’t know what know what the stat is, you can read up on it here.)

 

Kent Wilson

Perhaps we could discuss this from your latest “Thoughts on Thoughts” piece:

“Guys who lose a lot of puck battles end up with poor Corsis, and with the (slight) rise in the prevalence of that stat, I think those guys are going to be more exposed than ever.”

Is this something you intuited or is it something that’s been studied? I, personally, assume there could be a relationship there and in fact have thought it would be great if we could track puck battles to see if they correlate with possession (like the way Eric did with zone entries). 

That said, I’m not totally convinced this is necessarily true, particularly if the player has other well developed skills that may compensate for poor puck battling abilities (on the flip side, I think it’s possible to have a lousy corsi even if you’re strong in the trenches due to poor skating, puck play etc.). 

Related topic – the rise of corsi. Is that your assumption based on it’s prevalence in independent circles or have you heard whispers that some in the league are paying attention to it?

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Justin Bourne

I made the comment that guys who lose a lot of puck battles will have poor Corsis from my own experience as a player. When you have a linemate battling for a puck down low, and you’re in your position, you’re praying he comes out with it. If he doesn’t, you’re headed back on defense. So many times I remember personally getting bumped off pucks, and being partly pissed because I wasn’t going to get an offensive opportunity, but mostly because I knew I now had to skate the length of the ice (hard), and would likely be spending the shift in the d-zone. It’s pretty clear to me that losing puck battles will negatively affect your Corsi in a significant way.

I do agree that it’s possible to compensate for lost puck battles with other skills, specifically by making good decisions with the puck. (Though, you’d have to be making *great* decisions with them in the neutral zone to make up for something as damaging as losing battles.)

One thing I hope people who follow Corsi know, is that it’s mostly a decision-making metric, at least in my mind. Guys who turn the puck over a lot have their Corsi hurt. Guys who can’t figure out a way to get the puck out of their D-zone have their Corsi hurt. It’s largely mental. And I don’t follow the stat crazy-close, I just think I have a good grasp of the things that dictate the direction of the puck. Something like good skating can help you win a puck race or two and improve your Corsi, but that happens a time or two a game. You probably touch the puck and need to make a decision 20 times a night.

As for the “(slight) rise of Corsi,” it’s purely an assumption, made likely because I’m more submersed in hockey stats and info than I ever have been before (we have fancy-statters Cam Charron and Daniel Wagner who write for Backhand Shelf, so editing their work exposes me to it more), but I do believe you’ll see more of it in the future. I did an interview on HNIC Radio on Wednesday, and during it Kelly Hrudey said he was having lunch with someone the next day who was going to try to teach him more about advanced analytics. Which is to say, people are noticing them, Corsi in particular.

And for one final note, I don’t think Corsi will be considered all that “advanced” in the near future – I mean, it’s a pretty simple metric – when dude is on the ice, which way does the ice tilt?

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Kent Wilson

Regarding your take on puck battles and corsi, I largely agree with you based on my own experiences playing the game, as well as watching and scouting. However, I still think it requires some study before we can say anything definitely (which would require finding some way to track puck battles of course). I think Eric T’s investigation of zone entries and the effect of neutral zone play on possession last year (it’s apparently pretty significant) is why I’m somewhat skeptical of board play and puck battles necessarily influencing corsi to a great degree – even in spite of my own experiences and assumptions.

That said, if we somehow find a way to track puck battles and discover they indeed play a major role, I wouldn’t be at all surprised.

I also agree that corsi is or more less a “decision metric” with the caveat that a player’s skill level has to reach a certain threshold in order for him to be a positive possession player, no matter how well he thinks the game.

Finally, it’s interesting to hear that “advanced stats” are trickling their way up the food chain, at least as far as mainstream media is concerned. As you say, corsi isn’t actually all that “advanced” and is rather intuitive once you get past the strange nomenclature and focus on what it actually means. BTW – if Kelly Hrudy wants someone to help on the #fancystats front, I can suggest a few names…

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Justin Bourne

While we’re on the topic of suggesting names, can we agree that the nomenclature for advanced stats is in desperate need of a makeover? I’m a guy making a conscious effort to get to know and understand advanced stats (out of fear of becoming a dinosaur), and my favourite stat so far, PDO, eluded me for months and months despite me coming across it several times because what the truck does it stand for? Passing Defenses Offensively? Pardon Darren Octopus?

The answer, as you most certainly know, is that it was created by a commenter (I believe on an Oilers blog?) who went under the name “PDO.” (PDO is a metric that measures luck.) “Corsi” was created by Jim Corsi (also Oilers-related). “Fenwick” by Matt Fenwick. How confusing is this to your average fan? Nobody in baseball is asking what a guy’s “James” is (after Bill James, creator or sabremetrics). They use acronyms like BABIP (batting average on balls in play) and OPS (on-base plus slugging). It just makes sense. Anyway, that was a tangent.

Two final things from your last email before we wrap this up: you’ve highlighted two key areas where teams self-scout far more than most fans realize – neutral zone play, and puck battles.

In the ECHL, AHL, college and beyond, coaches will generally ask the healthy scratches (or legit injured guys, whoever’s in the press box) to track a few stats. Hits are almost always one – love those finished checks! – and puck battles are usually in the mix too. Turnovers are constantly tracked (you can imagine how a healthy scratch can skew the stats of a guy he’d like to replace, which makes for some fun inner-team drama).

Teams consider the worst giveaways to be anywhere within 10 feet of either blue line – make enough, and find yourself on the bench, and maybe taking stats the next day. Whatever the case, coaches put a lot of stock in a guy that plays safe (minimal turnovers), and those that emerge from 50/50 puck battles with the biscuit frequently.

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Kent Wilson

Yeah, the common names for many of the advanced stats came from a series of conversations and debates over the years amongst a number of people, so they were just kind of stuck with short hand nouns that the few talking about them recognized out of convenience. At the time, no one was really thinking “hey, it’s going to be tough to popularize this stuff with such confusing names.” 

On Jim Corsi, he was actually a Buffalo Sabres goalie coach who originally used the shots at net metric to evaluate his team’s goaltenders. Vic Ferarri and other Oilers bloggers converted it to the possession stat we know today. 

It’s interesting teams internally count stuff like puck battles and turn-overs. Of course, that sort of accounting can be limited in it’s usefulness since you’re generating a limited data set about a very small segment of the league’s population. The next step is to count league wide so you can compare outcomes across teams and correlate puck battles with other measures like corsi, goals, wins, etc. 

Comments (4)

  1. Good stuff guys. I usually email Justin when I’m drunk.

  2. A great option to use instead of Corsi is “Total Shots”, which has actually been seen on Nashville Predators broadcasts for a few years. It’s a natural complement to Shots On Goal, which is already well-understood by fans.

    If you put “Shots On Goal” and “Total Shots” right next to each other, it’s very easy for fans to understand, and to extend that to a rate stat for players or teams, you could call it “Total Shot Differential” or something.

  3. I love advanced stats, but one player that has always confused me when examining advanced stats is Tyler Kennedy. Is there any way Cam, Kent, or someone can do an in-depth explanation on Kennedy? Is Kennedy just the perfect storm of someone that can drive possession without it translating into more goals? On a side note I can not wait to see how removing Jordan Staal for an entire season will impact Kennedy’s numbers.

    • It is important to look at “who a player plays against” and “in which situations your coach plays that player.”

      http://nhlnumbers.com/uploads/Image/Pittsburgh.PNG

      Better players tend to get more ice time. The other team tends to match their best defensemen against your best offensive players. Matching forwards tends to be the result of both coaches but your best defensive and two way players tend to matchup against the other teams top forwards. Of course, if your offensive players are SO good the other team is forced to use their best players defensively against them (e.g. ->Malkin<-).

      Looking at the graph there are 6 Pit forwards the other teams focuses on before Kennedy (and that is NOT including Crosby). And there are 6 forwards that have a more defensive or two way defensive game then Kennedy.

      Looking at zone starts, Kennedy had 57% offensive zone starts for the season.

      So you have a player with favorable zone starts, who plays on a deep team resulting in significant minutes against the other teams bottom 6 forwards and bottom pair defensemen. All of which can give you a positive corsi; even when you aren't actually the one driving puck possession. Which means corsi really does need to be put into perspective to be useful.

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