The Bruins’ spending spree in free agency this past summer might have augmented their forward corps and re-shuffled their goalie rotation — but you could make the case that no segment of Boston’s roster has undergone a transformation as drastic as its blue line over the past few years.
Once anchored by franchise stalwarts such as Zdeno Chara and Torey Krug and supplemented by promising youngsters like Charlie McAvoy, Brandon Carlo and Matt Grzelcyk — the former have now all departed, and the latter are now tasked with being the leaders of a D corps with an average age of just 26.
Add in a mid-season trade of Mike Reilly last year as a transition weapon and the UFA addition of Derek Forbort as a stay-at-home presence, and Bruce Cassidy has had plenty to juggle when it comes to getting this revamped blue line to reach its full potential.
So far, those results have been … a bit mixed.
All things considered, the B’s are still holding court as one of the top defensive clubs in the league — ranking seventh in the NHL in goals against per game (2.62) and first in expected goals against (1.98).
And yet, while some key cogs like McAvoy are excelling as expected — Cassidy’s efforts of getting his D pairings to gel has been a bit of an arduous process.
And when it comes to assembling the puzzle that is Boston’s D corps, one of the square pegs has been an unlikely culprit.
Amid all of the turnover on Boston’s blue line over these last few years, Carlo has often served as a safety blanket in Cassidy’s lineup rotations — with the shutdown D serving as an effective anchor on Boston’s second D pairing.
Even when Carlo’s usual partner in Krug signed with St. Louis in 2020, the following campaign saw the B’s defenseman present promising returns with a number of other puck-moving blueliners in Matt Grzelcyk and Reilly.
In Carlo’s 58 minutes of 5v5 ice time with Reilly last season, the Bruins held a 40-14 edge in shots on goal. A Grzelcyk-Carlo pairing only had 44.2% of their faceoffs set in the offensive zone, but Boston still managed to hold a 51-37 advantage in scoring chances over their 98:13 of 5v5 ice time together.
Sure, the Bruins still had plenty of question marks entering this season when it came to finding a spot for Forbort and replacing Kevan Miller further down on the depth chart.
But trying to get a Carlo-led pairing to find some traction three months into the season? Can’t say that was necessarily on Cassidy’s docket this year.
A Grzelcyk-Carlo pairing has had the most reps over the years, but the encouraging production they’ve put forth in the past hasn’t translated to the 2021-22 campaign.
In the 185:13 of 5v5 ice time in which Carlo and Grzelcyk have logged reps together this year, the Bruins have been outscored, 9-3.
Of course, pivoting to Reilly-Carlo is far from a poor contingency plan — especially considering that it opens the door for a Grzelcyk-McAvoy reunion on Boston’s top pairing.
But Reilly-Carlo have also posted uneven returns together so far this season — with opponents holding the advantage in scoring chances, 47-41, during their 105:07 of 5v5 ice time together.
(Over the years, opposing scoring chances have regularly dissipated during Carlo's shifts - but that hasn't been the case this year. It's quite startling to see Boston's expected goals rate spike when Carlo's out on the ice.)
As of right now, it appears as though Cassidy plans on giving Reilly-Carlo another look coming out of this COVID-impacted pause — although Grzelcyk could remain in the rotation if more adjustments need to be made.
“I think he had a good fit with Grizz in the past,” Cassidy said of Carlo. “This year, maybe not quite as smooth as in the past. Why is that? Is that because our team isn't going as well? Is that because some pucks are going in the net more frequently than maybe in the past? There's probably a lot that goes into it. So he's going to play with Mike Riley coming out of the break here. And I have Grizz with Charlie. … We'd like to see them settle in.”
Carlo has not been hesitant when it comes to voicing his preference for a D partner with a vastly different skillset from his own. But when it comes to assessing the play of that second D pairing and the best tandem that the B’s have assembled with Carlo, the best results have come when Carlo has been logging shifts with a similar stay-at-home skater in Forbort.
As unconventional as it might be to load up one D pair with both of Boston’s perceived lockdown blueliners, it’s hard to argue with the numbers.
As expected, a Forbort-Carlo pairing has rarely received favorable starts in their 66:34 of 5v5 ice time together — with just 21.8% of their faceoffs set in the offensive zone. Given all of those reps in Boston’s own end, it’s pretty much a given that Boston’s shot share and other puck-possession metrics likely wouldn’t be that kind to Forbort-Carlo.
And yet, while opponents have a 44-37 edge in shots on goal during that 66:34, the Bruins are actually outscoring foes, 6-2, during that stretch.
A D corps featuring Forbort-Carlo on the second pair could be an intriguing reshuffle, especially considering that it allows Grzelcyk-McAvoy to remain intact and could give Reilly easier matchups on the third pairing next to either Connor Clifton or John Moore.
And even though it doesn’t seem such a configuration will be the move starting on Saturday, it sure seems like Cassidy’s tinkering with Boston’s D corps will remain a fluid situation until they finally find the right fit next to Carlo.
"Obviously, I've moved some people around, some of that was getting to know Derek, where does he best fit,” Cassidy said. “So obviously it affected sometimes who Brandon's partner was going to be. But again, I can't say this year — there's been one (pair) that has been better than the other.
“Brandon's a good hockey player. When he's on, doesn't matter who his partner is. It's the same with McAvoy be quite honest. And moving guys around, it's about finding their own game first and then obviously complementing one another. … We just like them to sort of recapture their individual games, which will make the partnership better.”