The Bruins have a dominant first line.  

David Pastrnak, back with Brad Marchand and Patrice Bergeron, scored both goals in the Bruins’ 3-2 loss on Saturday to Washington. The three forwards landed 15 of the team’s 33 shots. Coach Bruce Cassidy matched Bergeron’s group against Washington’s dangerous line of Jakub Vrana, Nicklas Backstrom, and T.J. Oshie and held them scoreless. 

This is what the Bruins need them to do.

Of the Bruins’ nine forwards after Marchand, Bergeron, and Pastrnak, five were full-time minor leaguers last year or close to it: Sean Kuraly, Danton Heinen, Austin Czarnik, Jake DeBrusk, and Jordan Szwarz. 

Anders Bjork was a Notre Dame junior. Matt Beleskey finished the season as a healthy scratch for half of the first round of the playoffs. Riley Nash and Tim Schaller were bottom-six NHLers. 

Ideally, the class structure would not exhibit so much inequality.

Together, Marchand, Bergeron, and Pastrnak make the Bruins look like a pumpkin teetering on toothpicks. They turn defense into offense. They wear out the ice in the offensive zone, even if they don’t produce a scoring chance every time. The collective pedigrees and experience of the other nine forwards make the outcomes of their shifts more unknown.

This could be partially solved if Bruce Cassidy kept Bjork with Marchand and Bergeron. The coach could roll out Pastrnak as a second wave of attack.

But Cassidy believes stacking his top trio and possibly chasing the puck for the other lines’ shifts is the lesser of two evils — the latter being not knowing how Pastrnak will play apart from his buddies.

When Cassidy puts Pastrnak with Marchand and Bergeron, he knows exactly what he’ll get out of No. 88. Marchand and Bergeron perform the heavy lifting of hounding opponents, causing turnovers, and initiating the attack. Pastrnak plops the cherry atop the sundae by emptying his bag of offensive tricks: beating defenders one-on-one, ripping off one-timers, and going to the net to clean up the litter his linemates produce.  

The Capitals, especially John Carlson and Brooks Orpik, delivered sticks and shoulders to Pastrnak whenever possible. Such attention is natural given Pastrnak’s offensive gifts.

 In the second, Pastrnak drove to the net, reeled in Bergeron’s pass, and beat Braden Holtby at 3:37 for the team’s first goal. In the third, with Heinen streaking to the far post, Pastrnak sold Holtby on a cross-crease pass. When Holtby pulled slightly off his post, Pastrnak zipped the puck off the goalie’s right arm and banked it into the net for his second strike. 

Pastrnak’s blemish was a second-period turnover. Facing forechecking heat from Lars Eller, Pastrnak rimmed the puck from behind his net to Orpik at the point. Tom Wilson was in place to deflect Orpik’s shot past Tuukka Rask, stretching Washington’s lead to 3-1 with 1:10 remaining in the second. Pastrnak was on the ice with Beleskey and Czarnik, not Marchand and Bergeron. 

“He was on the ice for a goal against,’’ Cassidy said. “As a low forward, you’d like to see him have better chemistry breaking that puck out. But he scored two goals for us. Hard to be critical. That’s what he does best.’’ 

Pastrnak is not the same player without Marchand and Bergeron. Few would be.

It would be one thing if David Krejci were healthy. He is not. The No. 2 center has not played since Oct. 19 because of a back injury.

Krejci and Pastrnak played well together. During the last three games of their second-line partnership, Pastrnak scored three goals and two assists against Vancouver, Vegas, and Arizona. On Oct. 21, the first game Krejci missed, Pastrnak scored two goals with Schaller as his center. 

But Pastrnak’s game turned quiet. His four-game goal-scoring streak stopped on Oct. 26 against San Jose when he played with David Backes, landing a season-low one shot on net. 

Two nights later, with Backes as his center again, Pastrnak went scoreless against Los Angeles. Pastrnak was on the ice for both of the Kings’ goals, including the overtime winner when he lost a defensive-zone draw to Anze Kopitar. Against Columbus, it was probably no coincidence that Pastrnak recorded the first of three assists when he returned to the first line.

For whatever reason (the stoutness of the Marchand-Bergeron combination, lack of familiarity with another center, greater defensive attention), Pastrnak’s performance, away from the first line, dips to a degree that Cassidy cannot endorse. For now, his home is on the top line, even if that leaves the other three trios at risk of getting their teeth kicked in.

“That’s the biggest reason — to keep David a little more involved with guys he’s comfortable with,’’ Cassidy said of sticking with his power line. “Now if he should develop something with one of the other centermen, we’ll certainly look at it. But I think that’s just the easiest answer right now to get the most production out of him.’’

In theory, Pastrnak’s skill set should decrease his reliance on a disher. Ottawa’s Mark Stone, for example, is more dangerous when Derick Brassard threads pucks his way. Pastrnak’s straight-line speed, creativity, and shiftiness should make him a threat whenever he has the puck, regardless of who deposits it on his stick. 

But so far this year, Pastrnak has been neither productive nor dependable enough apart from Bergeron and Krejci for Cassidy to consider him a reliable three-zone right wing next to Szwarz, Kuraly, or Nash. This compromises the Bruins against deep teams like Washington. Once Alex Ovechkin and Evgeny Kuznetsov finish their shifts, Nicklas Backstrom and T.J. Oshie are next over the boards. Even third-line center Lars Eller is capable of putting up points.

“He can generate his own offense,’’ Cassidy said. “We could probably put him out there with a lot of different players and he’ll find a way to find some pucks and get his shot off. I think it’s his overall game. He’s still 21 years old. I think that’s where Bergy and Marsh really pull him along and develop him into a complete player. They hold him accountable, maybe more than a Kuraly can now or Nash. They’re finding their own game. They’re not in a position to worry about anyone else. That’s no disrespect.’’

As constituted, Lines 2 through 4 cannot be expected to be consistent scoring threats. They are simply not built that way. 

The first line, however, has the skill and experience to put pucks in nets and keep them out of their own. Given the tattered lineup, each of the threesome’s shifts is more critical than usual. The Bruins need their lead dogs to bite.

Fluto Shinzawa can be reached at fshinzawa@globe.com.