Photo Credit: Tom Szczerbowski/USA TODAY SPORTS

Many of us who write about hockey from a statistical standpoint are fond of using Corsi, otherwise known as shot attempt ratio, to describe the general flow of play when various players or teams are on the ice. The idea is that a team with a ratio above 50% is doing well at controlling the game, while a team below that mark is getting outplayed. While Corsi is a good high-level indicator, especially at the team level, it does have problems in terms of evaluating individual players. The biggest problem is that since Corsi takes account of all shot attempts while a player is on the ice, we don’t have any indication of how much credit or blame to assign to each player.

The best way to tackle that problem is to build more granular data sets. One of the most promising ways of determining individual player impacts is by measuring their performance in the neutral zone. Neutral zone play has strong correlations to both shot attempts for and shot attempts against, which makes it a good way to assess some of the things individual players are doing well (or poorly) in the battle to outshoot your opponent.

For the 2013-14 season, Corey Sznajder tracked neutral zone data for every team in the NHL, and he made that data available to backers of a crowd-funding campaign. After spending two years working as a consultant for an NHL team, Corey decided to resume that project and is now tracking neutral zone data for the 2016-17 season. The in-progress data is available to backers of Corey’s Go Fund Me or his Patreon, so I’ve got data for all of 2013-14 and part of 2016-17 to work with.

In this post, I’m planning just to look at the Leafs defencemen and just at their contributions at the defensive blue line, but there’s much more data that I can explore in other posts later on, including the neutral zone numbers for forwards and at the offensive blue line.

ZONE EXITS



To set a baseline, let’s look first at the full season numbers for all of the current Leafs defencemen who played in the NHL in the 2013-14 season (which means no Zaitsev or Carrick). I’ve also excluded Matt Hunwick, for whom I have just 18 minutes worth of data. This first table is zone exits, or how well each player did at getting the puck out of the defensive zone.

Player Exit% Possession% Jake Gardiner 24.5% 21.8% Martin Marincin 24.6% 19.1% Morgan Rielly 27.7% 23.7% Roman Polak 26.0% 20.1%

Exit% is how likely a player was to get the puck out of the defensive zone each time he touched the puck, while Possession% is how often a player’s exits resulted in his team maintaining possession of the puck.

It’s worth noting that Polak (STL), Hunwick (COL), and Marincin (EDM) all played for teams other than the Leafs in 2013-14, so their numbers can’t necessarily be compared directly to Rielly and Gardiner as they were playing under different defensive systems and with different teammates. I also must point out that Matt Hunwick’s numbers are likely not too accurate as they cover just 18 minutes of ice time. But this at least gives us a bit of a baseline for these players.

Let’s take a look at the same data for this season, and we’ll add in the rest of the Leafs defencemen. This data covers only 15 games, about 1/3 of what the Leafs have played so far, but it’s still a decent sample size, and I can return to the numbers later on when more games are tracked to see how it holds up.

Player Exit% Possession Exit% Connor Carrick 74.6% 52.1% Jake Gardiner 78.7% 53.3% Martin Marincin 75.3% 27.6% Matt Hunwick 69.4% 39.5% Morgan Reilly 76.2% 52.0% Nikita Zaitsev 59.8% 38.5% Roman Polak 69.0% 22.5%

The most obvious thing here is how much better Rielly and Gardiner are compared to their numbers under Randy Carlyle. They’ve both tripled how likely they are to get the puck out of the zone on any given puck touch in the defensive zone. This is probably the area where the coaching change from Randy Carlyle to Mike Babcock is most obvious, as the Leafs were dreadful at leaving the defensive zone with possession when Carlyle was coaching.

Connor Carrick also looks quite good here, with numbers comparable to Rielly and Gardiner. He’s likely got a bright future ahead of him.

Matt Hunwick winds up looking OK here. He’s not up to the level of the top guys but given his salary and ice time that’s not a fair expectation anyway. He seems to be holding his own for a player being asked to play a reliable third line role.

Roman Polak and Martin Marincin both come away looking pretty bad here. Both players get the puck out of the zone with possession at less than half the rate that Rielly, Gardiner, or Carrick does. Polak gets the puck out of the zone at the same frequency as his primary defensive partner, Matt Hunwick, but does so successfully only half as often. I’ve heard many Leafs fans lately say they think Hunwick’s been playing better in a reduced role while Polak is still struggling, and this data certainly backs that up, at least as far as zone exits are concerned.

ZONE ENTRY DEFENCE



Next let’s look at how well they did at preventing zone entries in 2013-14, how well they defended the blue line and kept the other team from getting into the offensive zone with the puck:

Player Carry% Break-up% J. Gardiner 67.9% 6.5% M. Marincin 62.80% 11.60% M. Rielly 68.0% 5.2% R. Polak 65.80% 6.50%

Carry% is how often the puck was successfully carried into the offensive zone while playing against these players, while break-up% is how often the player stopped the puck carrier by taking the puck away from them (as opposed to preventing an entry by forcing a dump-in).

We can see in this data that Rielly and Gardiner struggled to prevent carry-ins, while Marincin was very good at breaking up plays at the defensive blue line.

What if we look at the numbers for this season?

Player Carry-in% Break-up% Connor Carrick 67.4% 9.3% Jake Gardiner 57.6% 7.1% Martin Marincin 58.2% 7.3% Matt Hunwick 57.4% 11.5% Morgan Reilly 60.2% 6.5% Nikita Zaitsev 66.0% 4.9% Roman Polak 62.8% 5.1%

The player who looks best here, perhaps surprisingly, is Matt Hunwick. He has by far the best rate of breaking up zone entries, while his carry-in% is about even with Jake Gardiner as the best on the team. Some people will be surprised to see how good Gardiner’s numbers are, but I don’t think there’s any reason to be. As I argued this past summer, Jake Gardiner is very good defensively.

Martin Marincin continues to defend reliably in the neutral zone, with numbers very close to Gardiner’s. This has always been the area where Marincin has excelled, helping to overcome some of his shortcomings in terms of puck-handling (as we saw above).

Morgan Rielly isn’t at the top of the team here, but for a player who has struggled defensively in previous seasons, I think the result here is pretty good. He’s showing clear signs of improvement, and he’s playing tougher minutes than Gardiner or Hunwick. His rate of breaking up plays at the blue line definitely still needs work, but the signs are more positive than they used to be.

The two players with the worst results are Roman Polak and Nikita Zaitsev. Zaitsev, in particular, comes across looking unimpressive, but given that being a hard-nosed defensive player is supposed to be Polak’s niche, it’s difficult to view these numbers as anything other than a disappointment for him.

If we combine the zone exit data with the zone entry defence data, the player who comes away looking the best is certainly Jake Gardiner, who is at or near the top of the team in both respects. After Gardiner likely comes Morgan Rielly, whose zone exits are excellent, and his entry defence has been getting much better.

Surprisingly, to me at least, Matt Hunwick comes off looking pretty good across this data. He isn’t as good with the puck as Rielly or Gardiner, but he’s around the middle of the defence in zone exits and right at the top in defending the blue line. It certainly appears as though Roman Polak is the major problem on that pair, and that Hunwick may very well be fine if given a better partner (like Frank Corrado).

Connor Carrick’s numbers suggest he’s a work-in-progress, a player with some exciting puck skills but who still needs to clamp down on the defensive end of things.

Marincin and Zaitsev both have numbers that are disappointing, I think. Zaitsev, in particular, does not look like he’s up to the top-pair role he’s being asked to play, at least in terms of his performance at the Leafs’ blue line. Finding an upgrade on Zaitsev to play those big minutes with Rielly looks like the Toronto’s biggest need at the moment.

As for Roman Polak, there’s not really much positive to see in his results here. Defensive zone play is supposed to be his forté, but his numbers here simply don’t bear that out.





