The Islanders had an important advantage over the Bruins in Game 5

Kyle Palmieri scored one of the Islanders' three power-play goals, this one in the second period.John Tlumacki/Globe Staff

The Islanders lack in star power, but they play with a touch of swagger, requisite patience, abundant discipline and, most important, ample finish.

It was their finish around the net, especially on the power play, that paced their 5-4 win over the Bruins Monday night at the Garden, and now the Bruins are at the precipice of having their season finished.

It was an atrocious night for the Bruins penalty killing squad, in part because it was forced to operate without injured blueliners Brandon Carlo and Kevan Miller, who undoubtedly would have helped to negate or rub out some of New York’s repeated good looks at the net.

The Isles went 3 for 4 on the man advantage, picking apart what this season was the NHL’s second-best PK team — albeit with Carlo and Miller as main contributors.

Reminder, in case anyone forgot: teams never, never, never have enough blueliners for the postseason. The decision not to define a meaningful role for Zdeno Chara looks increasingly misguided and painful. No guarantee that Big Z would have prevented the Isles from picking apart the PK unit like a $9.99 buffet, but his looming presence and reach and wingspan at least might have made the exercise a little harder than a Harlem Globetrotter layup drill.

The Islanders were awarded three penalties across the first two periods, and cashed in on all three, each time torching Boston starter Tuukka Rask with their first shot. Three power plays. Three shots. Three goals, all mixed into what was a 4-2 lead after 40:00.

Rask did not come up with the big stop when needed, and ultimately surrendered the cage to rookie Jeremy Swayman for the third period. The veteran Boston goaltender was not sharp, evident from the start of the night when he yielded rebounds on the Isles’ first two shots on net.

Rask has hinted since the start of the postseason that he has been dealing with an injury. Yet, until Monday night, he was impressive, submitting the kind of goaltending capable of pacing a team to a Cup. That’s not where his game was in Game 5.

But the Bruins, who also gave up too many free looks at even strength, were at their worst when forced to play a man down. The Isles each time were left with primo chances. Mathew Barzal scored his only 32 seconds after Sean Kuraly was whistled off, followed by Kyle Palmieri (Matt Grzelcyk off for a borderline cross-check) and then Jordan Eberle (Chris Wagner in the box for a high-stick).

The Carlo-Miller losses proved too much to handle and their relief was too green.

“We had opportunities to clear on every PK,” said a clearly frustrated coach Bruce Cassidy. “Some of them on the [defensemen] are tough, they are under pressure. [Sean] Kuraly had one he just has to shoot down the ice — he should know better than that. Been on our team a long time. A big part of our PK. You’re not making plays there — get it down the ice.”

Jarred Tinordi, one of the tire patches acquired because Chara walked to the Capitals, broke a stick on one of the kills. Charlie Coyle handed his to the big defenseman and then was unable to cut down a key shot.

Charlie McAvoy can’t get a stick on a bouncing puck in the first period of Monday's game.John Tlumacki/Globe Staff

“You can’t help that … that’s the luck of the draw sometimes,” added Cassidy. “And I think Charlie [McAvoy] behind the net, had a tough one. But he’s trying to clear it. You’re not going to get every puck down, but having the mind-set of clearing it … first get it out of the zone and then worry about what you have on your plate next.”

Connor Clifton, pressed into PK duty because of the injuries, was in position near the left post on the Palmieri backdoor strike, but did not stop the Josh Bailey pass coming in from the right circle.

“Just not able to get it done there,” said Cassidy, later adding, “I don’t put it all on the personnel tonight, but there are some guys out, no doubt, that do a great job killing penalties. And we miss it.”

Now with a 3-2 advantage in the best-of-seven series, the Isles can send the Bruins packing with a win Wednesday night at Nassau Coliseum — what would be their third straight triumph for the No. 4 seed in the East. History shows, in series tied at 2-2, the Game 5 winner goes on to clinch 78.8 percent of the time.

Bruce Cassidy and the Bruins have been pushed to the brink. How will they respond in Game 6?John Tlumacki/Globe Staff

There is an outside chance Carlo could be back in the lineup, but virtually no chance for Miller, still recovering from a high hit by Washington’s Dmitry Orlov in Round 1.

It was physical, nasty at times, and the Bruins repeatedly did not get awarded penalties for the same chintzy infractions that put the Isles on the power play. Carping about officials is a grand waste of time, and a very old story, but there was an alarming disparity in calls.

The frustrated Cassidy, upset that the Islanders weren’t called on like infractions, talked openly about a narrative that the Isles play with haloes over their heads.

“The New York Saints,” he said.

The Bruins wanted to get back to volume shooting, and they were successful, firing 76 attempts while the Isles launched only 35. But again, the Isles didn’t have to shoot much when each time on the PP their first attempts found the back of the net.

The Islanders are tough in the scoring areas, resilient and disciplined. In other words, a typical Lou Lamoriello team, reminiscent of when he ran a tight, efficient, Cup-winning ship in New Jersey.

Those Devils squads were boring (remember: the Trappist Wonks), but they were solid, tough and disciplined. They had better goaltending (Martin Brodeur) and a premier defenseman in the rugged, hard-hitting Scott Stevens. That’s not the ’21 Islanders. But they’re one win away from proving big results don’t always require big names.