Zach Aston-Reese has the Best Defensive Stats in the NHL. How?!

The Penguins bottom sixer is a master of killing time.

For most hockey fans, “defensive play” entails specific events centring around the defensive zone - stealing the puck, blocking shots, finishing checks, winning battles behind the net, etc. Players considered to be elite two-way players are typically guys who are very active in their own end, breaking up passing plays and creating turnovers.

This isn’t necessarily the case if you take an analytical approach. When analysts like EvolvingWild and Micah McCurdy discuss defence, they are conceptualizing it like this: the fundamental object of defence is to prevent your goaltender from facing quality chances against. Those events listed above are just part of how players achieve that goal. This approach implies that we must broaden the scope of what can be considered defensive play, meaning that almost everything on the ice has a defensive component: pinning a puck along the wall in the offensive zone, pressuring a defenceman trying to break out, maintaining possession offensively, etc. Anything you do that keeps the puck away from your goalie is ultimately serving that purpose.

Which brings us to Zach Aston-Reese (or ZAR). He’s a bottom six forward for the Pittsburgh Penguins who you probably mostly remember for getting hit by Tom Wilson in the 2018 playoffs. If you follow or read the work of analysts who put a lot of stock in stats, you might have seen his name come up improbably in the Selke conversation. That’s because by models that track a player’s isolated impact on defence (as it was described above), Aston-Reese ranked best or second-best in the league across the board.

No regular player in the league was on the ice for fewer expected goals against per sixty minutes than Aston-Reese, and when those numbers are adjusted for context, quality of competition, zone starts, etc. he still ranks second behind Colorado’s Valeri Nichushkin. Here’s his analytical profile this season:

Looking at this impact visualized is even more impressive. Per HockeyViz, check out this heatmap of where shots against the Penguins are taken when he’s on the ice. As you can see, they’re facing far fewer chances from within a radius of 40 feet compared to league average.

Aston-Reese does not have a particularly prominent role in the Penguins’ stacked forward group, as you might expect. He plays most of his minutes on a shutdown line with Teddy Blueger at centre and Brandon Tanev on the right wing, which is the 4th line when the Pens are healthy and the 3rd line when they aren’t. But this doesn’t mean that he plays easy minutes.

Despite ranking 12th in TOI/GP among Penguins forwards, he played pretty significant minutes this season thanks to injuries. He also gets deployed against top competition very often; he played the fourth most minutes against top competition on his team, fifth per game and fifth as a percentage of his total time on ice. On top of that, he was actually best when playing against those players, with a 51.8% Corsi and a +3.7 Corsi relative to his teammates. Despite being regularly tasked with facing really tough assignments, his line was the best defensive trio in the league this season.

Many Pens fans are under the impression that Aston-Reese is a fraud, receiving credit for the hard work done by his more visibly talented linemates Brandon Tanev and Teddy Blueger. Both of those players are stronger skaters than ZAR, handle the puck more, and seem more active in the play; therefore, the eye test would suggest, #46 is more of a passenger than a driver. But that story doesn’t really fit with the stats:

When ZAR was without his two most common linemates, his defensive numbers were hurt slightly (although they were still excellent), but he really didn’t seem to have much of a problem playing with guys like Sam Lafferty, Jared McCann, Dominik Simon, and Dominik Kahun. In fact, his expected goal generation and expected goals percentage were even slightly higher. The same isn’t true of Tanev and Blueger, who were even worse offensively and just average defensively when that same set of players were subbed in in his place. Clearly ZAR is the secret ingredient that makes the line work.

So how does an otherwise unremarkable player playing difficult assignments have such eye-popping results?

ZAR’s Eye Test (or, How to Be Bored While Watching an 8-6 Game)

Because I’m a Pens fan, I already watched almost all of Zach Aston-Reese’s games this season. That gives me a basic sense of what he seems to do well, but I admit that I usually pay slightly more attention to Crosby, Malkin, Guentzel, and Letang. A few days ago, Ian Tulloch of the Athletic asked me if I had any insights on how ZAR’s incredible results came to be, and I admit I came up pretty empty. So with NHL.tv’s 2019-20 archive free for the time being, I picked two games to watch: his best defensive game of the season (November 27 vs. Vancouver) and his most average/representative game (October 22 vs. Florida).

I honestly think that the core of Aston-Reese’s “defensive” brilliance actually comes down to maintaining puck possession in the offensive zone. In both games, ZAR’s line spent entire shifts wearing out their opponents along the boards behind their own net and just generally being pains in the ass. Typically their shifts would involve a dump-in with Aston-Reese going to retrieve the puck. Despite the fact that Tanev is clearly a faster skater, ZAR was actually far more active on the forecheck. This is reflected by the microstats: according to Corey Sznajder’s stat tracking, he ranked 20th in the league among forwards in puck retrievals per 60 minutes, first among forwards who played more than 15 games for the Pens. Aston-Reese would either send the puck along the boards or tie up the defenceman, allowing one of his linemates to keep the play going. This was such a crucial part of the unit’s effectiveness that it makes me think that it might be the reason that the line doesn’t work without him.

Tanev and Blueger tended to be more visible once established in the offensive zone, and Aston-Reese rarely carried the puck. However, while the unit doesn’t have the talent to consistently generate great scoring chances, when the puck did get to the middle of the ice Aston-Reese was usually the one in the soft area ready to take the shot. Something I also kept noticing is how frequently Aston-Reese moves to his off-wing to support the forecheck, battle for pucks, or make himself open for a scoring chance. Oftentimes this led either to a puck battle win or forced a defenceman to make a hasty clear out of the zone that ended up back in the Penguins’ possession. The line as a whole was very mobile, with all three players fluidly switching positions to maintain pressure. Despite all of this movement, I never saw Aston-Reese get exposed coming back; he always had time to get back to the left side.

To be fully honest, his defensive zone play didn’t make a huge impression on me. Looking over my notes from the two games, there are only a few instances where he was very noticeable in his own end. This is partially a function of how infrequently his opponents were actually able to enter the zone and establish possession. In one memorable sequence, Aston-Reese improbably cut off Evgenii Dadonov from gaining the blue line on the right side of the ice, and then swung back to the left side and stopped Jonathan Huberdeau from doing the same. Once in his own end, Aston-Reese played pretty deep in his zone, which wasn’t what I was expecting. He was very active along the boards, and almost always seemed to make the right play to chop the puck out of the zone and over a defender’s stick. His line’s M/O was the same as in the offensive zone: kill time.

Conclusion

Zach Aston-Reese is a perfect illustration of why the eye test and defensive analytics so often disagree. It also provides an indication of why we should broaden our notions of what constitutes defensive play - or at least recognize the distinction between the two ways of conceptualizing it. From a casual eye test, he doesn’t stand out at individually at all - at best he seems like an effective third wheel bringing some physicality. His awkward skating stride, magnified by playing alongside a burner like Tanev, doesn’t help, nor does the frequency with which he misses prime scoring opportunities. But it’s the fact that he can maintain his incredible shot suppression regardless of who he’s playing with combined with his effectiveness on the forecheck and along the boards that is what makes him a great defensive player.

It might be unfair to compare Aston-Reese’s game to that of a more traditional two-way forward, because the Penguins’ shutdown line is so exclusively focused on killing the clock by controlling the puck along the offensive boards. Players who suppress expected goals against while playing a more active offensive game such as Valeri Nichushkin, Blake Coleman, and Mark Stone should probably receive more credit, as their games involve taking more risks and not just killing time.

But at the end of the day, Zach Aston-Reese does exactly what you would ask of a shut-down bottom-six forward, especially one playing on a team that has so many offensive weapons. The Penguins can deploy ZAR against other teams’ best players, knowing that in all likelihood what they’re gonna see is 30-40 seconds of forechecking, board-battling, and puck-ragging. And at the end of the day, the best defence is not letting your opponent have the puck. Ever.