BOSTON — The Bruins have had a pretty good idea over the last few years of who would be playing alongside captain and No. 1 defenseman Zdeno Chara on the first pairing.

Johnny Boychuk, Dennis Seidenberg and Dougie Hamilton most recently occupied that spot, and regardless of who was playing with Big Z, that pairing was one of the NHL’s best in preventing goals and driving puck possession.

Now that Hamilton is gone, the Bruins need someone to step up and fill the void. Zach Trotman, a 24-year-old defenseman who took over the right side on the top pairing when Hamilton missed the final 10 games of last season, is the best choice for this job at the start of training camp.

“He came into camp in really great shape,” Chara said of Trotman after Thursday’s training camp conditioning tests. “He’s always been one of those guys — bigger, strong, physical presence. He’s showing that he’s very committed. He’s going to have a great shot to make the team.”

Trotman, with just 17 games of experience at the time, did a tremendous job after being called up in March to replace Hamilton. He helped the Bruins drive possession by controlling 53.52 percent of even-strength shot attempts, and he also made a strong impact defensively using his reach, size and positioning to break up scoring chances and win puck battles. He was on the ice for just three even-strength goals, and Boston had a .956 save percentage with him on the ice over that 10-game span.

It was a great 10-game sample for Trotman, especially with those games carrying quite a bit of importance because the B’s were trying to clinch a playoff spot. The next step for Trotman is playing at or near the level of last season on a consistent basis. It’s a lot to ask of someone with 27 games of NHL experience, but the Bruins can afford to be patient and deal with the growing pains.

If not Trotman, who else could play alongside Chara? Well, there’s not many quality candidates.

As the chart below from War on Ice displays, Seidenberg played against tough competition last season, but his ability to drive possession (highlighted with the red circle) was subpar. McQuaid and Miller also aren’t good enough defensively to prevent the opponents’ top lines from generating shot attempts or creating quality scoring chances.

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McQuaid and Seidenberg, in particular, struggled to prevent scoring chances during 5-on-5 play last season. McQuaid had a minus-16 scoring chance differential, while Seidenberg was at minus-73. To be fair, they did receive more defensive zone starts than Trotman and Krug, but Chara faced some of the toughest competition in the league — while dealing with a knee that was less than 100 percent — and still posted a 54.39 scoring chances-for percentage.

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Trotman could play with a little more of a mean streak, but he does use his 6-foot-3, 210-pound frame when advantageous. Like Hamilton before him, Trotman could learn a lot from playing with Chara, while also facing the challenge of defending first- and second-line forwards nightly.

There’s lots of uncertainty surrounding all four forward lines and each of the three blue line pairings entering the start of camp Thursday. It will create lots of internal competition, specifically among the defensemen.

Trotman has a great chance to fill an important role for the Bruins this season, and it will be interesting to see how he responds to the competition over the next three weeks.

Thumbnail photo via Brace Hemmelgarn/USA TODAY Sports Images

Thumbnail photo via Dec 17, 2014; Saint Paul, MN, USA; Boston Bruins defenseman Zach Trotman (62) against the Minnesota Wild at Xcel Energy Center. The Bruins defeated the Wild 3-2 in overtime. Mandatory Credit: Brace Hemmelgarn-USA TODAY Sports