Bruce Cassidy was clearly joking when he called his own decision a “stroke of genius, huh?!” after the Bruins’ 5-2 win over the Flames on Tuesday night.

The decision — swapping in David Backes for David Pastrnak on his prolific first line — was a tough call that absolutely shifted the momentum of the game. Backes provided the grit the line’s been lacking lately, and his five hits and two assists paced the chippy win. It was the right call in a physical game, but what does it mean going forward?

And what’s up with Pastrnak? When he’s hot, Pastrnak plays a flashy, fun game.

Maybe Cassidy summed it up best back in December when the 21-year-old was coming off a 12-game point streak: “I like to see Pasta do his things.”

The generally hyper-skilled right winger has been in a bit of a slump (by his standards, at least) since his turnover in the ugly loss to Buffalo Feb. 10 resulted in a goal against. He’s gone without a point for the last three games, but the costly turnovers on a defensively sound top line are his main issue — especially on a team itching to get back to its “pucks-to-the-net-bodies-to-the-net” mentality.

An unnecessary slashing penalty at 18:34 of the first was the final straw for Cassidy as he swapped Backes in.

“He knew he took a bad penalty,” Cassidy said. “He came out of the box ready to go. He was physical, he wanted to give back. He knew he messed up and that’s the growth you like to see. You don’t like to see a guy sit at the end of the bench and pout. He responded the right way, played hard and helped us win the hockey game.”

But the coach, who tends to show a refreshing amount of respect for his players, made it clear: This isn’t a dog house.

“We keep everything honest in our building…David and I always talk,” he said, “I love David’s passion for the game, his willingness to compete. We just have to remind him every once in a while how to compete, how to manage the puck and how to best help the team.”

Pastrnak’s ice time dropped from 18:17 against Buffalo to 13:42 at New Jersey to a season-low 12:02 against Calgary. He also recorded a season-low 13 shifts, and Cassidy said it was a game-specific tweak, but that we’ll have to see what happens going forward. Whatever line he ends up on, Pastrnak doesn’t seem to mind.

“I don’t know, you know, to be honest, don’t really think about it, he said. “I don’t mind playing with anyone, I think…I can find chemistry. Try, want to be better, and we’ll see. I was trying to get better.”

That effort manifested with a hit on former Bruin Dougie Hamilton and a slap shot attempt through the first minute of the second. The immediate (correct) response and Pastrnak’s nonchalant attitude about what some might call a demotion back up Cassidy’s notion that this isn’t a dog house…it’s just a reminder.

With 82 games in a regular season, sometimes you just need one of those.