What are Bruins’ ideal D pairings for playoffs?

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The Bruins are about to have their full arsenal of defensemen for the first time in three months, not to mention the first time since Mike Reilly was added to the group at the trade deadline.

The Bruins are planning for Brandon Carlo to return Tuesday night in New Jersey after missing the last month with an oblique injury. There is still some load management going on with a couple other defensemen, as Reilly will sit Monday night for “maintenance” while Kevan Miller will sit Tuesday, as the Bruins still don’t want to push him to play back-to-back nights due to his knee.

But if all three of them play later in the week -- say, Thursday night against the Rangers -- it would mark the first time since Feb. 10 that Carlo, Miller, Charlie McAvoy and Matt Grzelcyk have all played in the same game, and obviously the first time they’ll have all played together with Reilly.

This all comes just in time for the playoffs, but now the question is what makes the most sense in terms of pairings. It’s a topic we discussed on the latest episode of The Skate Podcast, which you can listen to below. For more context, read on.

Before getting into what it appears Bruce Cassidy is going to do, here are some numbers on what some of the most used and most likely options have done at five-on-five this season, all courtesy of Evolving-Hockey. We’re leaving out Steven Kampfer and Jarred Tinordi as well as some pairings involving Clifton or Jakub Zboril that seem unlikely at this point just for the sake of condensing this, but obviously it’s possible injury or poor play could lead to some minutes for Kampfer or Tinordi or force some pairings not covered below.

Lauzon-McAvoy: 297 minutes, 57.0% shot attempts, 14-13 goal differential
Grzelcyk-McAvoy: 285 minutes, 61.3% shot attempts, 14-6 goal differential
Zboril-Miller: 172 minutes, 54.5% shot attempts, 4-4 goal differential
Clifton-Carlo: 115 minutes, 50.8% shot attempts, 2-3 goal differential
Reilly-Clifton: 91 minutes, 63.2% shot attempts, 8-1 goal differential
Grzelcyk-Carlo: 87 minutes, 57.1% shot attempts, 5-4 goal differential
Grzelcyk-Miller: 66 minutes, 61.8% shot attempts, 3-1 goal differential
Reilly-Miller: 66 minutes, 51.6% shot attempts, 1-3 goal differential
Lauzon-Miller: 35 minutes, 42.1% shot attempts, 0-3 goal differential
Lauzon-Carlo: 26 minutes, 40.0% shot attempts, 0-1 goal differential
Reilly-McAvoy: 16 minutes, 46.9% shot attempts, 2-1 goal differential

Starting with who plays next to McAvoy, the debate is Grzelcyk or Lauzon. Clearly the results favor Grzelcyk, which makes sense -- Grzelcyk is better than Lauzon. But it appears that at least to start, Cassidy is going to split them up.

While that may seem like an odd choice on the surface, there’s a solid rationale here: Cassidy wants one of his top puck-movers (McAvoy, Grzelcyk, Reilly) on each pair to provide balance and avoid having one pair that may not be mobile enough to hold up in the playoffs (i.e. a Lauzon-Miller pairing that has really struggled in limited minutes together).

Cassidy has already started this realignment in the last couple games, moving Lauzon back up next to McAvoy (where he started the season), putting Grzelcyk with Miller, and teaming up Reilly and Connor Clifton. It would seem the plan is for Carlo to replace Clifton next to Reilly, but we included the Reilly-Clifton pair in the chart above because it’s worth noting that they have been very good together. It’s something Cassidy should keep in the back of his mind in the event of injury or poor play forcing a lineup change.

Cassidy’s thinking makes sense. While there is a clear drop-off from Grzelcyk to Lauzon next to McAvoy, the hope is that the gains you get elsewhere -- specifically with Grzelcyk next to Miller -- outweigh it, and that balance and being able to roll three pairs you feel good about is better than being top-heavy and having a third pair you don’t really trust. Reilly-Carlo sounds promising in theory, and giving them some run over this last week of the regular season makes a lot of sense.

Plus, Cassidy can always go to Grzelcyk-McAvoy during certain situations where the Bruins need some offense, as he did last year when Grzelcyk took a lot of offensive shifts from Zdeno Chara.