What we learned: Struggling Bruins drop third straight

The hits just keep on coming for the Boston Bruins.

Even a 2-0 lead at the end of the first period against the lowly Ottawa Senators couldn’t prevent the Bruins from unraveling Thursday night at TD Garden.

A dreadful second period began with Jeremy Swayman leading the Bruins onto the ice instead of Linus Ullmark. The latter became the latest Bruin to succumb to injury after taking a puck to the face early in the first period.

Ullmark stayed in after the medical staff examined him from the bench. He made eight stops before ending his night after 20 minutes of play.

Marc McLaughlin and Jesper Froden gave the B’s a 2-0 cushion with their first-period tip-ins on their respective third and first career NHL goals.

If only Bruce Cassidy’s club had the same fortune in the final 40.

Swayman didn’t receive much help in his relief appearance, though he did everything he could to keep the Bruins in it with multiple quality saves on breakaways and odd-man rushes.

The Sens, who got on the board a mere 47 seconds into the middle stanza on Brady Tkachuk’s 27th goal of the season, took the lead with a pair of power-play markers from Josh Norris (a 5-on-3 tally) and Tim Stutzle following a Mike Reilly high-sticking infraction and a rather soft hooking call on Patrice Bergeron.

The second-period issues, the defensive miscues and the sputtering power play ultimately doomed the visibly peeved Bruins as they dropped their third consecutive game for the first time this season.

“Frustrated, as I said, is a useless emotion. So I’m not frustrated; I want to correct things,” Cassidy said postgame.

Here’s what we learned from Ottawa’s 3-2 victory.

The power play has turned into a momentum killer

The Bruins didn’t have Matt Grzelcyk’s services for Tuesday’s tilt against the St. Louis Blues. He watched Boston’s power-play struggles from the Garden’s ninth-floor press box as they extended the skid to 18 straight attempts without a goal.

“Getting the chance to watch up top, we’re better when we’re moving the puck quickly. Maybe guys are just thinking a little bit too much. It’s something we address on video quite a lot the last few days and the last few weeks,” Grzelcyk said. “But going out there and executing [is though].”

Grzelcyk returned for Thursday’s tilt. So, too, did Boston’s struggling power play.

Without David Pastrnak’s potent one-timer for the fifth straight game, the B’s power play has hit a funk. More often than not during Pastrnak’s absence, they’re searching for the perfect play and forcing pucks through congested areas instead of shooting and attempting to generate quality secondary scoring chances.

The ugly trend continued with Boston’s 0-for-5 showing, extending its power-play goal drought to 23 straight chances.

“We’ve got to move the puck quickly and play off the shot a little bit more. Sometimes we’re trying to find a seam and it’s not there, and we’re forcing plays a little bit,” Grzelcyk added after watching the Sens score twice in their six power-play opportunities. “Maybe if we have a little more of a 5v5 mentality and get pucks to the net, we can get to the net and play off a rebound. And then that’s where the skill takes over.”

Well, the Bruins could also use more 5V5 offensive production, particularly from some of their usually reliable options.

The Bruins’ core hasn’t picked up the slack

The Bruins fired 42 shots at Anton Forsberg. Both of their goals came on tips from Froden and McLaughlin. They established building blocks for a bounce-back outing from those first-period tallies.

Instead, they self-inflicted, deviating from their structure from the opening 20 and ultimately needing to turn to their reliable scoring options for help following a disastrous second period. And once again, Cassidy didn’t receive any scoring help from his core.

The Bruins posted 11 goals in five games without Pastrnak. Opposing D’s have turned their attention to shutting down the top line of Marchand, Bergeron and Jake DeBrusk. The former, arguably Boston’s top playmaker, hasn’t lit the lamp in six games.

The trickle-down effect reared its ugly head over the last week. Hall hasn’t found a comfort level since Pastrnak’s injury, with three points in his last five games. The third line became a source of transition with Cassidy benching Trent Frederic following his ill-timed second-period roughing penalty against the Blues leading directly to Torey Krug’s equalizer. Coyle, the centerpiece of the third line, hasn’t tallied a point since netting the overtime winner in Tampa last Friday.

Even in their rut without Pastrnak, Cassidy doesn’t see this trend continuing for long. Yet, his concerns with the team’s offensive setup of late remain prevalent.

“The lack of finish with some guys is obviously hurting us right now, and we’re not shooting at the appropriate time. Certainly, some guys we rely on on a regular basis every night aren’t putting up the numbers right now for whatever reason. We’ll look at that a little closer,” Cassidy said. “I don’t think it will go on forever. They’re too good. Some lines need to get back to their game.”

Boston’s roster depth became thinner with Ullmark’s exit

The Bruins wanted to get Swayman back on track following his rough string of starts over the last few weeks. For the most part, they’ve hung him out to dry during his start against the Blues and again two nights later against the Sens.

Only this time, Swayman had to seal the deal in a relief appearance.

Swayman stopped 21 of 24 shots in the losing effort. More importantly, he looked comfortable tracking the puck and remained poised amid a slew of breakaway attempts and odd-man rushes, particularly in the third.

But Swayman’s encouraging development came at a time when the injury-plagued Bruins couldn’t afford another scare. And indeed, they encountered another nightmare on Thursday.

“He got hit in the head with a shot early and then left the game obviously. And I haven’t heard an update since,” Cassidy said. “We kind of put [Swayman] in a bad spot there with all the penalties we took in the second. He certainly found his game as the game went on and gave us a chance to win. But we’ll have to see how Linus is [Friday] and see if it’s a long-term thing.”

Like their Boston counterparts, Troy Grosenick and Kyle Keyser provided a decent tandem down in Providence. Even with just four career NHL appearances, the Bruins would likely call up the 32-year-old Grosenick over the 23-year-old Keyser if Ullmark winds up missing time.