Boston’s line of, from left, David Pastrnak, Brad Marchand and Patrice Bergeron might be the best on hockey, but splitting up the stars could benefit the team as a whole. But Coach Bruce Cassidy doesn’t plan to tinker with it until the Bruins are healthy. Mary Schwalm/Associated Press

For two games, the Bruins got all the second-line scoring they could have hoped for in back-to-back 5-2 wins over the Montreal Canadiens and Philadelphia Flyers.

But through 15 games, and especially after an anemic shutout loss to the Calgary Flames, those two games seem more like an exception to the rule. If the top line of Brad Marchand, Patrice Bergeron and David Pastrnak have a rare bad game, as it did on Sunday against the Flames, then the Bruins seem to have little chance of a win.

It makes you wonder sometimes whether that line – still inarguably one of the best lines in hockey – is a luxury the Bruins can no longer afford, especially with David Krejci back home in the Czech Republic. Perhaps a Craig Smith or Nick Foligno could bump up to play with the time-tested pairing of Marchand and Bergeron. Could that create a more dynamic second line that features wingers Pastrnak and Taylor Hall together around center Charlie Coyle?

Asked whether he’s thought about breaking up that line any more this year in light of the spotty secondary scoring, Coach Bruce Cassidy didn’t rule it out. In fact, he expects to do some tinkering at some point. But Cassidy said now is not the time.

“I’ve always said I’ll do it when we’re healthy and there’s somebody who can go up there,” said Cassidy on Monday. “At the start of the year, Coyle was our second-line right wing because we didn’t have any right wingers. So we weren’t going to do it then. We’re just starting to get healthy.

“I think that line really complements each other well, even though you could say ‘They could play anywhere.’ Well, of course they could. But they do do a good job of complementing each other. … It’ll probably happen at some point. I just want to make sure it’s the right time.”

There is no guarantee of more widespread production if Pastrnak is moved elsewhere. But if the better teams in the league continue to shut down the B’s, they may have no choice but to look at their lineup differently.

HAULA NEEDS SURGE: Speaking of secondary scoring, or lack thereof, Erik Haula scored his first goal of the season against New Jersey on Nov. 13, but it did not open the floodgates for him. In the three games since then, he has one primary assist.

Haula was part of the Bruins offseason free agent spending spree, signing a two-year deal worth $2.375 million annually. He also had a strong training camp and exhibition season. But now he has just a goal and two assists in 15 games, which is not enough. How can more production be squeezed out of the third-line center?

“We’re still getting to know Erik, he’s still getting to us, so I don’t think there’s an automatic answer,” said Cassidy. “Usually when you’re in position to receive passes, you use your speed through the neutral zone and that’ll help open up offense. A good example was Smitty’s goal (in Philadelphia on which Haula assisted). We broke out in the right spots and we’re going as a group. I think it’s a little more of a line rush line with (Jake) DeBrusk and Smith when he’s out there. Obviously when that happens you’ve got to fill three lanes and get the puck at the right time to get attacking. That’s an important part, so that’s a five-piece combination. Offensive zone play, you’re starting to see that fourth-line combination starting to generate because they know where each other are.”

Cassidy said some of the ask of that line as a whole will be to create more off the forecheck.

“We’ve been asking for some of those O-zone situations out of Jake for a while now, so you’ve got three new bodies working together and they’re going to have to buy into that and we’re going to have to do a better job of getting them to accept it. That’s hockey a lot of nights against good checking teams. They’re not going to give that neutral zone stuff,” said Cassidy.

SWAYMAN BACK: After a rough outing on Sunday, goalie Jeremy Swayman was one of two Bruins who took to the ice on Monday, the other being the rehabbing Trent Frederic.

Cassidy is not concerned about the rookie’s confidence.

“Goalies have to put things behind them. They’re going to have good outings, they’re going to have a few that aren’t great and they have to recognize what they have to do better and move on,” said Cassidy. “I think his confidence will be fine. If it was three or four in a row, that’s when you start worrying about the young guys. It hasn’t been.”

Meanwhile, Tuukka Rask was again on the ice earlier in the day as he continues his rehab from hip surgery. He’s expected to be ready to play again sometime after the New Year. If the Bruins continue to get spotty performances from their tandem, it’s hard to imagine the club not offering the free agent a contract when he’s ready to play.