Earlier this season, Islanders coach Barry Trotz admitted he’d be remiss to split up Anders Lee and Mathew Barzal on the team’s top forward line.

But when Barzal missed a handful of games with an injury earlier this month, it forced the Islanders to play Brock Nelson in that role. Sometimes, the best ideas come by accident.

Since Barzal’s return, the top line has stayed that way, with Nelson centering Lee and Beauvillier. It is easy to see why.

After the Islanders’ 4-2 win Saturday over the Stars, the threesome has a 59.26 expected goals rate compared to a 57.14 actual goals rate. Nelson added to the tally with a hat trick against Dallas to buttress Lee’s recent points-scoring tear.

As it turns out, this configuration works, and the Islanders are reaping the rewards.

“Leesy can keep pucks alive down low and then Beau and Nelly, they’ve had good chemistry for a number of years here,” Trotz said. “It gives us some weight down low, keeps more pucks alive in the offensive zone.”

For a long time, Trotz said, he wanted Lee next to Barzal to add some size to the skillful center’s left. Recently, he’s come to realize that may not be so necessary.

This first line can create off the forecheck, as opposed to just the rush. That was evident in Nelson’s second goal, assisted by Beauvillier and Lee after the Islanders forced the issue in the Dallas zone.

“I think Beau’s playing extremely well,” Nelson said. “Lots of speed, obviously, quickness, can make plays. You can try to get open, [he] can get you some pucks, some good looks. And Leesy, he’s been one of the hottest players in the league. You get him some pucks right now, he’s feeling good.”

Nelson’s hat trick, completed via an empty-net goal 20 seconds before time expired, came almost via coincidence. All three goals were in the third period of a game in which the Islanders walked the tightrope.

That made for a postgame atmosphere in which Nelson’s second hat trick of the season (the first was in Montreal in early November) was a bit of an afterthought.

“Yeah, it’s nice,” Nelson said. “I think it’s a byproduct of a nice pass by Beau, the power play, just being in different spots, it’s nice to contribute.”

“Anybody who on our team gets a hat trick, it’s probably a good day,” Trotz said.

It was then pointed out to him that all three came in the same period.

“Yeah, good period,” he said. “It’s all good.”

Asked if trade speculation was affecting Semyon Varlamov, who keyed the Islanders to victory with 37 saves, Trotz said he hadn’t heard that Varlamov would be dealt ahead of Monday’s deadline.

“It’s you guys speculating,” he said. “I haven’t heard anything that he’s going anywhere.”

Ryan Pulock’s second period slap shot goal clocked in at 100.8 miles per hour, per MSG.

The Islanders honored Jean Potvin, their former defenseman who died Tuesday, with a moment of silence and video tribute.