I’m playing around with some new metrics at the moment. They’re all related to the same sort of interest: pushing past Corsi% as a metric and getting into the stuff underneath it. As I’ve mentioned in a previous post, I’m calculating what I call an open play Corsi% – basically, I knock out the stuff after faceoffs and then the stuff I’m left with, theoretically, doesn’t have any faceoff effects. It’s just guys playing hockey.
I’ve lifted the phrase “open play” from soccer, where they talk about “open play” and “set pieces.” Basically, a set piece is a corner kick or when a player gets fouled and a free kick is awarded. Open play is what happens when the game’s just flowing. There’s an obvious comparison with hockey and when there’s a faceoff: teams can game plan for faceoffs in each location and what they want to do a bit more easily.
Two of the metrics I’m playing around with are the same concept, just for offence and defence. What I’m doing is breaking the game down into shifts by way of a proxy. For every time that a player’s on the ice for SF, I call that a shift. If there’s a shot within the next 60 seconds, I count that shot as part of the same shift. There’s going to be a bit of a fudge factor in this but not too much of one, I think – the new stats site Extra Skater ran a test of my methodology and found it was pretty much bang on with actual shifts. The downside to what I do is that I don’t count shifts on which there are no shots. The upside is that I don’t have to enter into the tangled thicket of the NHL’s shift data.
Anyway, so I end up with a count of how many shifts a player was on for 1 shot attempt for (SAF), 2 SAF etc. Same for 1 shot attempt against (SAA), 2 SAA etc. (Side note: shot attempts are the same as Corsi events: goals, shots, blocked shots and missed shots.) What I’m interested in is this: once we know that a shot attempt has taken place, how good are players at preventing the second attempt or, if they’re on the offensive side of things, at generating that second, third shot attempt.
What this gives me is a sort of breakdown of a player’s shifts and what percentage of those with at least one SAF were 1, 2, 3 etc. I can then create a number that answers the question “Given 100 shifts with at least one shot attempt, how many shot attempts for/against would we expect this player to be on the ice for?”
Whenever I’m introducing something like this, I like to do it by way of percentiles, so that I can illustrate the range. I also like to break things down between forwards and defencemen – you never, know sometimes you find some some unexpected differences between the two groups. So first up, we’ll look at the range in SAF/100+ SAF for forwards for the 2007-13 seasons.
A statement of the somewhat obvious: there seems to have been a gradual drift upwards in terms of the SAF/100+ SAF that forwards compiled. This may be a result of the NHL scorers getting better at crediting misses and blocks or teams beginning to shoot the puck more frequently or a combination or some unexplained third thing.
If you think about what we’re doing here, we’re starting to break how a player achieves his Corsi% down into small, specific chunks. In effect, what this asks is, “To what extent have generating multiple shot attempts once you’ve got the first one contributed to your Corsi%?”
Another statement of a potentially obvious fact: there doesn’t look to be a HUGE difference between the guys who are pretty good at this and the guys who are kind of bad. The difference between best and worst? Yeah, that seems pretty large. As far as the rest of it goes though, you end up pretty quickly with a sort of muddled middle without huge differences.
To illustrate things, we’ll look at two players who’ve been on different arcs these past few years: Sidney Crosby and Alexander Ovechkin. Ovechkin was, as we all know, a Corsi% monster who kind of seemed to slow down and has never really come back. Crosby wasn’t really one until recently. What does it look like if we graph their SAF/100 Shifts with 1+ SAF for the six years for which this data is available?
As it turns out, it’s pretty cool and it illustrates a lot. Ovechkin led NHL forwards in this stat in 2007-08 and 2008-09. He was a hair off the lead in 2009-10, finishing behind only Michael Grabner, who didn’t play a ton. He slipped in 2010-11, although he was still well above the 90th percentile. These last two years though…there’s just not a lot there. Hart Trophy last year or not, part of what made Ovechkin really cool to watch was the sort of maurading that went on, the sense of the Caps and Ovechkin dominating shifts. That hasn’t been around for a while.
Contrast that with Crosby. He was nothing special in this early on in his career and now, the last two seasons, he’s posted the highest SAF/100 Shifts with 1+ SAF (I’m trying to use descriptive names but you can see the appeal of just calling something like this by the name of the creator) of any NHL F. People talk about big, heavy teams and big heavy players and those kinds of players are the ones I’d expect to score well in this metric, which is really an indirect way of asking how well you control the game offensively once you get established. Haunches aside, Crosby’s neither particularly big nor particularly heavy but the Pens are the best team in the NHL at generating multiple shot attempts on a shift when he’s on the ice. Different ways to skin a cat.
What about defencemen?
You’ll notice, if you contrast this with the forwards, that each percentile for the defencemen tends to be a few shots higher. My suspicion is that this number tends to be controlled more by the forwards who are on the ice and that, as defencemen will play with all four lines, they get a dose of the ability to generate multiple SAF after one SAF of each forward line.
I suspect that fourth lines, in particular, lack the ability to generate multiple SAF after getting one, in conjunction with risk averse coaching staffs who don’t want them taking risks. I’ve put the list of forwards with fewer than 130 SAF/100 Shifts with 1+ SAF on Google Docs to illustrate what I’m talking about – lots of fourth line types, with the odd curiosity, like “What the hell was going on with the 2007-08 St. Louis Blues?” and “Why did Lennart Petrell get another contract in Edmonton?”
I’m going to talk more about these metrics and do the SAA stuff and introduce the third metric I’m looking at as the week goes on. I think it’s important to touch briefly on why doing this sort of stuff matters to people who want to know more about hockey though. The better the information that we’re generating about what goes on on the ice, the better the answers we can come up with as why things change or where problems lie.
Part of that will involve pushing past Corsi%, to try and figure out what makes it tick and whether some parts are more within the control of certain individuals than others. Eric Tulsky’s done some great stuff in this area, looking at zone entries. A fellow by the name of Pierce Cunneen is co-ordinating a project to track zone exits. The more people doing stuff like this, the closer we’ll get to figuring out things like the Ben Eager Conundrum (or the Patrick O’Sullivan Conundrum or the Eric Belanger Conundrum).
A lot of this stuff, I think it’s hard to catch with the eye. Can you catch, with your eyes, that the Pens are suddenly generating an extra 20 shot attempts with Sidney Crosby on the ice on every 100 shifts with shot attempt? I’m not sure I could although I’ll bet that multi-SAF shifts with Sid on the ice will catch my eye this year. As you can see by the breakdown of his 2010-11 vs. 2011-12 seasons, the difference is pretty dramatic but I don’t recall anyone saying along the lines of “Gee, all of the sudden the Pens are way more likely to generate multiple SAF on a shift with Crosby.” It might be too small to catch just by watching but it’s real and it’s affecting his results.
The flipside’s true with Ovechkin. I’ve heard all sorts of theorizing about why he hasn’t been the same Ovechkin of old but not a lot of breaking down of how his results have changed or theorizing based on anything beyond the fact that he isn’t producing results like old Ovechkin anymore.
I haven’t heard anyone talking the shape of the change of Ovechkin’s performance. Even this year, when he won the Hart Trophy, he’s still a shadow of what he was at 5v5 once. I’ve heard tons about him changing wings (more than even some members of the PHWA) but it seems to me that a big shift in what Ovechkin does and how he does it has been missed. It generates all sorts of questions like “Why?” and “Can it be fixed?”
If you were building profiles of your players with this degree of detail – and for all I know the Caps are – it’d give you something to work with your hockey technical people to try and isolate what’s changed and why. If you’re in the media and you’re responsible for covering a hockey team, understanding stuff like this so that you can ask intelligent questions seems a better use of your time to me than being the 30th person to tweet out line combos at practice. In training camp. When some of the names are guys who have a hard time getting into junior games.
My point, I guess, is that while there’s a pretty strong case for doing this sort of stuff because it lets us understand the game better, it also makes for better stories about the game. I find this Ovechkin/Crosby business pretty fascinating – Washington’s been a revolving door of coaches lately but if I were doing an in-depth piece on Ovechkin – and it seems like lots of people do – I might like to track down one of Boudreau’s assistants and ask about this. Or talk to Dale Hunter. Or Adam Oates. We’re getting to the point now with the numbers that we’re starting to be able to paint pretty good pictures of what happened on the ice and ask more pointed questions about why. Those questions don’t all have to be directed at the data.Email Tyler Dellow at firstname.lastname@example.org