After a 3-year drought, Bruins return to the playoffs

David Pastrnak (right) gave kudos to Tuukka Rask after the Bruins clinched a playoff spot.John Tlumacki/Globe Staff

Bruce Cassidy is coaching a playoff team, one that clinched its fate beyond Game No. 82 with a 4-0 win over Tampa Bay on Tuesday at TD Garden.

That Cassidy ascended to his current position required an unfortunate ending to his predecessor’s career. Cassidy does not take this lightly.

“Extremely gratifying,” Cassidy said of earning a postseason bid after replacing Claude Julien. “It’s not the circumstance that anybody wants to draw up. But it happened. You go to work, try to get the team where it needs to be, do the things that you feel are necessary to continue to get better. I thought we’ve done that. This is the first step. We’ll see where it goes from here.”

The truth is that the Bruins’ 18-7-0 sprint through Game No. 80 was very unlikely to happen without the catalyst of the coaching change. For whatever reasons — innovation, a more aggressive approach, a different boss delivering the message — the Bruins are a better team under Cassidy than they were under Julien. They have earned the right to enjoy hockey in spring because of their turnaround.

Perhaps Cassidy’s emergence initiated the revival. But it was the players who executed the dash to the postseason.

“It feels great,” goaltender Tuukka Rask said. “The city deserves it. The organization deserves it. We feel we deserve it, too. We worked hard all year to secure a spot. It took 80 games. It’s a good feeling. I think everybody can breathe a little easier now. But we’ve still got two games left and then the real games start. Great accomplishment.”

Late in Tuesday’s first period, Cassidy was faced with a dilemma. He had lost Brad Marchand, his leading scorer, because of a selfish below-the-belt stick to Jake Dotchin. Neither team had scored. Given five minutes to play with, the flammable Lightning could have lit up the Bruins for multiple one-up strikes.

Cassidy did what coaches are supposed to do: solve the problem. Marchand and Patrice Bergeron are one of his most trusted shorthanded pairs. They alternate penalty-killing shifts with Dominic Moore and Riley Nash.

Cassidy did what some coaches might not have done. He busted up Moore and Nash, a known shorthanded commodity. Cassidy paired Moore with Bergeron as his lead penalty-killing duo. Moore played 3:10 of the five-minute kill. Bergeron logged 3:01 of shorthanded ice time. Behind them, Zdeno Chara (3:30) and Adam McQuaid (2:24) killed the bulk of Marchand’s major.

The result: just two shots off the sticks of Ondrej Palat and Victor Hedman, both steered aside by Rask.

“Breaking up him and Nash was a bit of a gamble, because they do have some familiarity,” Cassidy acknowledged. “But sometimes a little separation isn’t bad either. It seemed to work. We gave it a shot. It worked the first time. It allowed Nash to use someone else with. I think they think alike, Bergy and Moore. So I thought there’d be some synergy or chemistry there.

“Sometimes you’ve just got to try and hope it works for the better. That’s what happened. They’re both good penalty-killers. I don’t see why they couldn’t do it together.”

It was a signature Cassidy move. If Julien had a shortcoming, it was sticking to something for too long. By the time a fix was required, too much time had ticked by for the repair to take hold.

Cassidy takes a different approach. He is quick to experiment. He is aggressive with most of his moves: trying new pairs, changing lines, and doling out shifts to the players who are most deserving.

With Moore and Bergeron leading the charge, the Bruins killed the penalty and went on the attack. Drew Stafford lifted the rebound of an McQuaid blast over Andrei Vasilevskiy’s glove for the winning goal at 5:56 of the second. David Pastrnak gave the Bruins breathing room by burying a Nash feed at 16:06 of the second.

Chara winged a power-play goal through Vasilevskiy’s wickets at 9:12 of the third. Pastrnak capped off the win with an empty-netter with 1:02 remaining in regulation .

Big Zee's blast that made it 3-0 🚨 pic.twitter.com/Uw8AgYuY9s

— Boston Bruins (@NHLBruins) April 5, 2017

Rask, meanwhile, stopped all 28 shots for his eighth shutout. Rask cracked under Tampa’s heat in his previous appearance against the Lightning on March 23. Rask saw three one-goal leads disappear, then handed away 2 points when he waved at a Jonathan Drouin slapper. Since then, Rask has regained his ace form, rolling off four straight wins and posting a .972 save percentage.

“He’s come back and looked structurally sound, controlling his rebounds, playing pucks well,” Cassidy said. “Pretty much every facet of his game is solid. I think in front of him, that breeds confidence. Now our D are able to get up and close their gaps and have the confidence that if they are a little bit off, the goaltender’s able to make the save.”

The Bruins are in third place in the division with two games remaining. On Thursday, they host Ottawa in what would be a preview of a first-round matchup. It is a scenario the Bruins would much rather prefer than falling into the wild-card slot and facing Washington in the opening round.

"You always want to be playing for the Ultimate Trophy." pic.twitter.com/XXtIiahf7S

— Boston Bruins (@NHLBruins) April 5, 2017

But after two straight seasons that ended with misses, the Bruins were simply satisfied after the win with what it meant.

“This one feels pretty special,” David Krejci said. “We fought hard. It was an up-and-down year, but we got the job done. I thought we played really well the last 20 or so games. So it feels really good.”