On Tuesday, the Lightning sent twenty-two year old defender Slater Koekkoek back to the club’s AHL affiliate in Syracuse. Predictably, the move sent the fanbase into an uproar.

Jason Garrison appears to be following the Matt Carle career arc, and Andrej Sustr seems to have stalled in his progression, so Koekkoek is the best shot the Lightning have to develop a capable second pairing defender behind Victor Hedman and Anton Stralman.

Koekkoek’s season hasn’t gone the way that some, including me, had hoped, but it doesn’t change his status as one of the keys to the Lightning’s ability to compete at the top of the Eastern Conference.

The Scenario

The team hasn’t yet given a reason for the demotion, but three scenarios seem viable:

The team wants Koekkoek to play a game in the AHL on Wednesday and will recall him back to Tampa for Thursday. I don’t see the logic here given how compressed the schedule has been lately, and that’s a lot of travel to get 15-20 minutes of time in the AHL. The team is concerned about sending either Luke Witkowski or Nikita Nesterov back to Syracuse because both would have to clear waivers. If that’s the case, one wonders why the Lightning would have recalled Witkowski for the back-to-back in Philadelphia and Pittsburgh when they could have recalled Matt Taormina instead, and avoided the waiver hassle. The team wants Koekkoek in Syracuse and prefers to keep Witkowski in Tampa. Given that head coach Jon Cooper scratched Koekkoek in favor of Witkowski as recently as Saturday against Philadelphia, I think this is probably the case. The rest of this article assumes that this is the scenario.

The Data

Analyzing defensive play is tough. We don’t have many stats that do a great job of isolating defensive impact. Much of defensive play is about positioning and anticipation. Good defense often leads to nothing happening, and measuring how much nothing happens is difficult.

This article is going to take a relatively simple approach. We’re going to look at shots for and shots against as well expected goals and expected goals for and against. All data here is score, venue, and zone adjusted via corsica.hockey.

Instead of looking at individual defenders, we’re going to look at defensive pairs and see what we can learn about how the Lightning have played with different defensive pairings on the ice this season. The top scatter plots below show the shot and expected goal metrics I’ve mentioned. The bottom bar graphs show shot and expected goal shares. What we’re hoping to accomplish is to identify which defensive pairings have played the best so that we can gain some context for the decision to demote Koekkoek.

Looking at the data presented in this way, we can quickly decide that Victor Hedman and Anton Stralman are the Lightning’s best pairing. They are second in shot share and first in expected goal share. We didn’t need to go through this exercise to confirm that, but in case anyone was wondering, yes, the Swedefenders are the best pair on the team.

Identifying the second best pairing on the team is almost as easy. Braydon Coburn and Koekkoek have the second-best expected goal share on the team, and the fourth best shot share. One could make an argument for Jason Garrison and Nikita Nesterov, but they’ve played far fewer minutes together, and considering that Coburn has been the third best defender on the team, I think Coburn and Koekkoek makes more sense.

The Implications

If we accept that assertion, demoting Koekkoek becomes an even more confusing decision. Why would the team split its second best pairing? The consequences of that decision are that the Lightning would be running pairings of Coburn with either Nikita Nesterov or Witkowksi and Garrison-Sustr.

While Coburn-Nesterov has been good in terms of shot share, they’ve given up lots of dangerous chances, which is why their expected goal share is so low. Garrison-Sustr is the opposite. They’ve been hammered in shots but haven’t given up as many dangerous chances, and thus have slightly better expected goal numbers. But neither has performed as well in both measures as Coburn-Koekkoek.

If the team would commit to Hedman-Stralman and Coburn-Koekkoek, the coaches would be left choosing from Garrison, Nesterov, Sustr, and maybe Witkowski to create the third pairing. As discussed above, Garrison-Sustr has been a bit better in expected goal share, while Garrison-Nesterov has been better in shot share. This leaves us right where we were at the beginning of the season when I wrote a piece suggesting that Sustr and Nesterov were basically on an level playing field and should get equal opportunity to earn more playing time.

That hasn’t happened. Sustr has continued to be a lock for the lineup when healthy, while Nesterov floats in and out of the lineup, even covering at forward at times. The Lightning did finally scratch Sustr for one game against Nashville last week. In that game, the pairings were Hedman-Stralman, Koekkoek-Coburn, and Nesterov-Garrison. That aligns perfectly with what we see in the data above. In that game, the Lightning outshot Nashville 54-25.

Unfortunately, goaltender Andrei Vasilevskiy struggled in that game, allowing four goals on the first eight shots, and the Lightning lost a game that they deserved to win. How the coaching staff interpreted that outcome is impossible to know, but Sustr hasn’t been scratched since then, and Koekkoek is back in Syracuse — so those are indicators that we might not see this arrangement again.

Drawing conclusions from a one-game sample would be irresponsible, but considering how that game went compared to other recent games, I would like to see that set of defenders get some chances to see if they can replicate those results.

Final Thoughts

The Lightning season has gone wrong for a slew of reasons: injuries, iffy goaltending, bad luck. All of those have factored into the Lightning’s struggles. But moves like splitting your second-best pairing by sending one of them back to the AHL don’t help the cause. Navigating an NHL season is hard enough without doing things that make in even more difficult.

We often hear coaches talking about controlling the “controllables.” Choosing which healthy players to play is a controllable. In this case, I think the Lightning are missing an opportunity to make an optimal lineup decision. I haven’t done any work to demonstrate the impact of the decision so I don’t want to make any grandiose statements about to what degree demoting Koekkoek hurts the team, but I do think we can say with reasonable certainty that his demotion is a net negative.

Hopefully, Koekkoek comes back to Tampa soon and the coaches reunite him with Coburn, because without that pairing, Tampa’s defense will likely look even weaker than it has over the last couple months.