Patrick Roy knows what he wants from Islanders, but can he get it?

All-Star Mathew Barzal’s broad, beaming smile, not to mention his words, provided a ringing endorsement of new coach Patrick Roy’s master plan for the Islanders.

Keep the defense but make the team more dynamic offensively.

It’s not a new idea. The onus is on Roy to make it work this time.

Former coach Lane Lambert, fired Saturday midway through his second season, preached that to start his first season. He tried to get the defensemen to push up the ice aggressively. It took just two months for Lambert to scrap that plan.

It almost certainly will take a few games for Roy to put a real stamp on his new team — he’ll get a second chance on Tuesday night when the Islanders face defending Stanley Cup champion Vegas at UBS Arena — but he’s not hiding his intentions through typical coach doublespeak.

To steal an old presidential campaign moniker, Roy is riding “The Straight Talk Express.”

Consider his lengthy and information-filled answer after the Islanders won his debut, beating the visiting Stars, 3-2, in overtime on Sunday night, when he was asked to grade any tweaks he tried to make in Game No. 1.

“Offensively and defensively, I thought we worked quicker,” Roy said. “Our [defensemen] are a little afraid to leave the net front. These are the habits they’ve had for a long time. But Adam [Pelech] was starting to go, leaving the net front and going. It’s just normal. It’s a trust thing. We need to trust each other and the D needs to trust the forwards and the forwards need to trust the D.”

By the way, broaching a lack of on-ice trust between the players is somewhat of an indictment of how they’ve been playing and how they’ve been coached.

“When we’re going to be more comfortable, we’re going to have a lot more heavy pressure in the D zone and I think that’s going to help our team break out and [spend] less time in our zone,” Roy said. “I haven’t seen the puck possession [time against the Stars], but I didn’t have a moment where I was like, ‘I can’t wait to see that puck leave the zone.’ I thought we did some good stuff in our D zone coverage.”

At the same time, Roy, unprompted, said 17 of the Stars’ 42 shots came off giveaways and pointed out that the Islanders will struggle to establish any time in the offensive zone if they keep turning the puck over with frequency.

The Islanders are 31st in the NHL in allowing 35.2 shots per game. Roy indicated he wants to see that number around 30.

So improve the defensive effort while creating more puck possession time in the offensive zone.

“I’m not taking anything away from what we’ve been told in the past because both sides of that can be effective,” said Barzal, who got a crash course in the importance of playing defense under Lambert and predecessor Barry Trotz. “But I think Patty’s philosophy seems to be a bit more possession, a little bit more aggressiveness all over the ice.

“Holding the puck, wanting to tilt the ice. So that’s music to my ears.”

Only if Roy can make it work.

Notes & quotes: Goalie Semyon Varlamov (lower body), who last played on Jan. 2, was activated off injured reserve and Ken Appleby was reassigned to the Islanders’ AHL affiliate in Bridgeport .  .  . President and general manager Lou Lamoriello is planning to meet with Benoit Desrosiers, 35, who was Roy’s assistant coach with the Quebec Remparts of the Quebec Maritimes Junior Hockey League from 2017-23, about a role in the organization.

By Andrew Gross

andrew.gross@newsday.comAGrossNewsday

Andrew Gross joined Newsday in 2018 to cover the Islanders. He began reporting on the NHL in 2003 and has previously covered the Rangers and Devils. Other assignments have included the Jets, St. John’s and MLB.