Islanders' head coach Patrick Roy, center right, watches the action...

Islanders' head coach Patrick Roy, center right, watches the action during the first period of an NHL hockey game against the Dallas Stars, Sunday, Jan. 21, 2024, in Elmont. Credit: AP/Mary Altaffer

Whistle? Patrick Roy didn’t need a whistle.

For one thing, he can whistle with no mechanical assistance, thank you.

For another, even when not whistling, he knows how to get everyone’s attention with his booming, French-accented voice.

So Roy began his first morning skate with the Islanders on Sunday by eschewing that traditional coaching accessory, then blew a figurative hole through a team in dire need of a jolt.

He stopped the action at Northwell Health Ice Center more than once to deliver instructions, gathered players to remind them the playoff push is at hand, and more.

Most of it was clearly heard by reporters standing in the concourse far from the ice surface, as if Roy was sending a message beyond the team itself.

Nine hours later, it was time to introduce himself to Islanders fans, and he did so in the best way possible with a 3-2 overtime win over the Stars at UBS Arena.

It was not pretty, and afterward Roy lamented too many turnovers and too many shots allowed. But the bottom line was all that mattered for now.

“We looked like a hockey team tonight,” said Mathew Barzal, who set up Bo Horvat’s game-winner. “It was nice to see . . . Just a massive win for us.”

Just as he was in the morning, Roy was a show unto himself during the game, constantly moving, shouting and encouraging players from behind the bench.

“I personally love it,” Barzal said. “All game, positive energy — just energy.”

Roy said simply, “That’s how I am.”

Apparently so.

After the morning skate, captain Anders Lee said, “It was evident from the moment he stepped in the room, the energy and passion he brought. You saw it. It’s there. It’s infectious, too.”

Even though the energy comes naturally to Roy, there is a method to it, too. It goes back to that playoff push thing. There is no time to lose.

There are only 36 games left in the regular season, and the Islanders have a coach who has few direct ties to the franchise or current roster. So this will be a crash course in learning the personnel, and vice versa.

Roy has not coached in the NHL since 2016 — when the Islanders played home games at Barclays Center and Jack Capuano was their coach.

On the player side, the Islanders’ veteran core has not heard a completely new voice behind the bench since Barry Trotz arrived in 2018. He was succeeded by his longtime assistant, Lane Lambert, who was fired on Saturday.

“I don’t want to go too fast,” Roy said during a long, engaging, bilingual chat with many more journalists than usually attend an Islanders morning skate. “I want to make sure they’re comfortable, step by step.”

This is a juggling act, and a balancing one, too.

One could argue that taking over a veteran team whose core has been together for years might work against a newcomer. But Roy views it as a bonus.

“I think it’s very positive,” he said. “Maybe there’s not that many of them that won the Stanley Cup, but there’s a lot of them that had good playoff runs.”

Roy, 58, is all in. He even shaved his beard in a nod to team president Lou Lamoriello’s longtime policy against facial hair.

“I told the players it was probably the hardest thing to do from the minute I took the job,” Roy said in French, as translated by Sportsnet.

Roy has been a master of marketing and media relations — after Lambert set a low bar in that area — but in the end, he will be judged by wins and losses, of course.

It will take time to see where he is headed with his X’s-and-O’s, but while he said he is no slave to analytics, he noted that the numbers do not lie.

He told the players that being substandard in everything from breakouts to puck possession in both the offensive and defensive zones is no way to win.

“I’m going to do a cliché here, but defense wins championships,” Roy said. “So we’re going to start worrying about our defense. I mean, I always believe if you break out the puck well, then you’re going to spend less time in your zone.”

Roy said he took too much for granted in his first head- coaching stint with the Avalanche in the mid-2010s and is in better position to succeed now.

“I’m a lot more humble as I approach this new adventure,” he said in French.

He said he wants a “partnership” with the players. He also wants them to buy into big dreams.

Roy recalled Canadiens coach Jacques Demers informing him and his teammates in 1992-93 that the team would shock the hockey world by winning the Stanley Cup.

“We were all looking around and said, ‘Did he look at our lineup here?’ ” Roy recalled. “But the man believed in it. So I want us to believe in ourselves.”

The Canadiens won the Cup in ’93.

The Islanders’ journey to get there, in ’24 or soon thereafter, restarted on Sunday.

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