The Bruins are what they are. They are a top-heavy team that needs its best players to be difference-makers. The rest of the lineup — rookies, AHL regulars, would-be healthy scratches — simply cannot be counted on to be reliable NHL contributors. 

So when the lead dogs failed to convert a 65-second five-on-three power play against the Toronto Maple Leafs in Saturday’s third period, the 4-1 result, to nobody’s surprise, did not swing in the Bruins’ favor. 

“We had a lot of chances to get back in the game, especially on the five-on-three,’’ said Patrice Bergeron. “We didn’t do the job. It’s on us. We’ve clearly got to be better, bottom line.’’ 

The Bruins do not expect Bergeron, Brad Marchand, and David Pastrnak to score on every shift. But they almost have to put in a goal every other time they take the ice, especially when Torey Krug and Danton Heinen join them for an extended two-man advantage. As a group, they have the skill, experience, and savvy to turn five-on-three power plays into game-breaking situations. 

The Bruins, who lost Friday in overtime in Toronto, 3-2, were only trailing by one goal Saturday when Andreas Borgman went off for tripping. Then when ex-Bruin Dominic Moore was whistled for tripping as well, the Bruins should have at least tied the game. Coach Bruce Cassidy called his timeout when Moore joined Borgman in the box, both to rest his alpha dogs and emphasize plays they should make on Toronto’s penalty kill. 

Instead, it was Toronto’s shorthanded men who did the best work. They pressured the Bruins at the points. They were hard on the puck. During the two-man advantage, the only puck the Bruins placed on backup goalie Curtis McElhinney was a long-distance Krug wrister. It is not the best option, not when Pastrnak’s one-timer, Bergeron’s ripper from the bumper position, and Marchand down low are all bona fide looks. But when pucks were bobbled and passes were off, those options never opened up. 

“We had a few looks where we were mishandling the puck,’’ Bergeron said. “I think it was more of that than just looking for the perfect play. We just weren’t making the passes that were there. The lanes were there. We just didn’t connect. We definitely need to have more shots. I think it was more not taking care of the puck than not forcing plays.’’ 

After the Bruins failed to score on the five-on-three, the Leafs got some life. They took advantage of the missed opportunity at 6:52. With traffic in front, the final layer being Brandon Carlo’s last-minute screen of Tuukka Rask, Morgan Rielly’s point shot slipped through bodies and into the net, giving Toronto a 3-1 lead. Patrick Marleau put the game away with an empty-netter at 18:13.  

“Around the net, they were better than us,’’ Cassidy said. “We’re frustrated. But we’re not discouraged. We’re playing hard. You go through these lulls where you need to be a little better. When you’re not, it seems to go against you. If you continue to play hard, things will go your way.’’ 

The Bruins finished the night in 14th place in the Eastern Conference. They are staring up at five other non-playoff teams just to make the wildcard cutoff. It’s early and the Bruins are hurting. But they are not in a comfortable position just about 20 percent into the season. 

“It’s a big swing,’’ Krug said of the 4 points Toronto recorded in the back-to-back set. “Division opponent. It’s pretty early to start looking at the standings and things like that. But these are big points. Game 82 is worth 2 points. Game 1 is 2 points. It doesn’t matter. We’ve got to do a better job of coming up with points. We’ll get back to work.’’ 

The Bruins’ power play (0 for 4, six shots on net) and their misfiring up-front execution cost them the game. Carlo didn’t help on the back end.  

Carlo was on the ice for two of Toronto’s four goals. It was a tough night for the second-year defenseman when the Bruins could least afford it. 

In the first period, with James van Riemsdyk applying forechecking heat, Carlo tried to hit Sean Kuraly with an outlet pass. But Carlo’s attempt was too hard and off Kuraly’s stick. Mitch Marner received Carlo’s turnover, walked into the slot, and picked the corner over Rask’s glove at 8:52 to give Toronto a 1-0 lead.   

In the third, Carlo’s unfortunate positioning in front of Rask took away the goalie’s eyes when he needed them the most. 

“I had a bad night,’’ Carlo said. “Nothing else to really say about that. I was trying to make plays. They ended up in the back of the net.’’