When puck possession isn't enough

If you're a forward-thinking hockey fan with an interest in advanced statistics, the Vancouver Canucks are a very peculiar case this season. The specific stats which are raising the most questions actually aren't that advanced at all: Corsi and Fenwick are simple metrics that measure everything a team throws towards the opposition's net (whether it hits the net or not), with the difference between the two being Fenwick doesn't count blocked shots. The value of these stats is based on the simple leap in logic that the more shots a team attempts, the more they have the puck. When people talk about puck possession, they aren't talking about actual time of possession, rather, they're referring to shot attempts.

As of this writing, the Canucks sit 2nd in the NHL in 5-on-5 Corsi behind the Los Angeles Kings and ahead of teams like the Chicago Blackhawks and Boston Bruins, who most people consider to be leading Stanley Cup contenders.

But as you know, the Canucks only have 4 wins in their past 15 games. So what gives?

Well for starters, Corsi is a "big picture" statistic, one that is more indicative of a team's future success than a reflection of their current place in the standings. Over a long period of time, the more shots a team attempts, the more goals they're going to score and the more games they're going to win. Every team goes through rough patches even if they're putting up good Corsi numbers, because there are any number of random events or lucky bounces that can impact the outcome in a small sample of games.

So this would suggest the Canucks are regularly outplaying the opposition and just not getting any bounces, right? Well, I don't think even the most optimistic fan could confidently claim that the Canucks have consistently outplayed their opponents this season. Are there other forces at work here?

The fantastic game recaps put together by our friends at CanucksArmy like to tally the scoring chances for and against each game. Rather than simply counting shots, they keep track of quality scoring opportunities around the net. I haven't done an official tally, but the number of times the Canucks have actually out-chanced their opponents this season is probably in the single digits. They're consistently giving up quality chances in their own zone, even against abysmal offensive clubs. The last game against Columbus is a perfect example: the Canucks outshot the Blue Jackets 38-27 but were out-chanced 15-7 according to CanucksArmy.

So the Corsi data is telling us that the Canucks are dominating the shot battle, but the chance data shows that they're consistently giving up more scoring chances than they're generating.

What the hell is going on?

Over at Backhand Shelf, Daniel Wagner (also one half of Pass it to Bulis) wrote an interesting piece on how Corsi and Fenwick, while valuable, aren't telling the whole story. I highly suggest you read the whole thing, but here are a couple excerpts:

"All of those shots, whether on goal, missed, or blocked, are a by-product of what a team is actually attempting to do. The result a team is looking for is goals and, to that end, a coach puts in place systems, tactics, and game plans in order to prevent scoring chances for their opponents and create scoring chances for themselves that will produce that result. The players then put those into action and, as a by-product, produce shots on goal, missed shots, and blocked shots.

...

It's not enough to simply outshoot your opponent: every NHL team knows this. It's why you'll never see players trying to game their Corsi by taking low-quality chances. What matters is goals and you score goals by doing things that hockey traditionalists love - making a good first pass out of the defensive zone, winning puck battles, creating turnovers in the neutral zone, going hard to the net, cycling the puck down low, etc."

What I think the Canucks are missing in this equation are the "things that hockey traditionalists love". It comes down to structure. Vancouver's defensive zone coverage has been suspect on several occasions this season, which is the main factor in giving up quality chances. The forward lines have been in flux and without strict definition of which is a "scoring line" and which is a "checking line". Without Ryan Kesler and Kevin Bieksa — the two most important players on the team in my opinion — a lot of guys are playing outside of their usual roles, and that affects the structure of the team's attack.

If a shot is a byproduct of puck possession, a scoring chance is a byproduct of doing the extra legwork to ensure that shot is from a dangerous position on the ice. That means winning puck battles and creating turnovers and driving the net. It's valuable to count missed shots not just because they imply possession, but because they imply there could be more opportunities created from that missed shot.

The Canucks aren't doing enough to earn those opportunities right now. Simply taking a ton of shots without a thought to where they're coming from is about as conducive to scoring as dry humping is to conceiving — it feels good but you're not going to get the results you're looking for.

The predictive power of Corsi and Fenwick has proved to be formidable, but they're only a part of the equation (albeit a very large one). The Los Angeles Kings were 2nd in the league in 5-on-5 Corsi last season and won the Stanley Cup, but they also had the inhuman goaltending of Jonathan Quick. Meanwhile, while Vancouver was eking out a lot of wins down the stretch, their possession data was cratering and they were an easy out in the first round.

Some will tell you that the Canucks being a top-5 possession team this season is a sign that they're eventually going to turn things around. It's certainly a great place to start. But if they're going to find their form again, they need to find the structure in their game that will help convert all that time with the puck into something tangible.