BOSTON – It’s not coach Jim Montgomery’s fault that David Pastrňák, Brad Marchand, Elias Lindholm, Pavel Zacha and Charlie McAvoy, the Boston Bruins’ five best offensive players, did nothing for 97 seconds when they played a five-on-three power play in the game. Tuesday first period.

It’s not Montgomery’s fault. Mason Lohrei fumbled pucks out of the defensive zone so consistently in the first period that he had to bench the second-year pro for the remainder of the period.

It’s not Montgomery’s fault that Marchand threw a puck so hard during a power play in the third period that the coach covered his face with his notes.

But it’s Montgomery’s responsibility to fix the many leaks the Bruins have caused this season, the most recent being Tuesday’s 2-0 loss to the Philadelphia Flyers.

It seems like a monumental task.

From start to finish, the Bruins performed at the minor league level. They passed pucks in skates. They botched the entry into the offensive zone. They made weak clearing passes that yielded little from the rush. They barely reached the front of the net.

The outcome could have been worse. Joonas Korpisalo made his third start and scored two goals. In the first inning, Korpisalo made a last-ditch kick save on Bobby Brink’s straight shot. Later in the first inning, Scott Laughton and Garnet Hathaway took the ice for a two-on-one shorthanded rush. When Laughton played a pass on the closing line to Hathaway, Korpisalo slid from right to left and glove’d the ex-Bruin’s attempt.

What the Bruins played on Tuesday was not up to NHL standard.

“We don’t make plays,” Montgomery said. “We don’t do enough to generate high-risk scoring opportunities. Whether that’s the will to go to those areas or not the right game plan, we’re all guilty of not coming out with a win tonight.”

The Bruins’ top six, including Charlie Coyle, struggled to get anything going against the Flyers. (Brian Fluharty/Imagn Images)

Think about the opponent. Philadelphia goaltender Samuel Ersson entered the night with an .872 save percentage in six appearances. According to Moneypuck, Ersson had saved -6.1 goals above expectations.

The Bruins gave Ersson a vacation.

Through 4:48 of total power play time, the Bruins placed just two pucks on Ersson. Due to the two-man advantage, they opted to stay still in their spread formation instead of moving around, creating seams and forcing the Flyers to chase. Montgomery’s subsequent adjustments — replacing Zacha at the net front with Justin Brazeau and starting a power play in the third period with the No. 2 unit — did nothing.

“On any team, your best players, your star players, have to carry the weight of the load offensively,” Montgomery said. “These are the players who are looking for power play. The violation is not an issue for us at this time.”

Some of this is expected. The Bruins fall short of the top six after the departure of Jake DeBrusk. Montgomery has gone through virtually the entire roster at No. 2 right: Brazeau, Morgan Geekie, Trent Frederic, Matt Poitras. On Thursday, even Mark Kastelic, normally the fourth-line center, got a ride with Marchand and Charlie Coyle.

But DeBrusk’s absence doesn’t explain the complete disappearance of Geekie, who has zero goals and one assist in nine games. It doesn’t explain why Marchand, Coyle and Zacha, all top-six forwards, have zero five-on-five goals among them. Even without DeBrusk, the Bruins should be better than 14.3 percent on the power play.

It seems like there is underperformance across the board.

“It seems like it’s a lot of things,” Montgomery said when asked why the Bruins couldn’t build on their overtime win over the Toronto Maple Leafs. “Some guys are still battling it in terms of their confidence and their ability to handle the puck.”

The Bruins are not as slow as they seem. But their shaky confidence leads to indecisiveness. They take too long making passes, shooting pucks and crashing the net. Everything is turned off.

“If you’re struggling offensively, you might just hold that stick,” Hampus Lindholm said. “When you’re on a hot streak, you usually take the puck and kill it right away. You don’t think. This game becomes much easier if you just play with your intuition.”

Ten games is no small example. The 4-5-1 Bruins are what they are, and that’s not good enough.

(Top photo: Brian Fluharty / Imagn Images)