The Islanders were one of the most disappointing teams in the N.H.L. this season, and Barry Trotz paid the price with unexpected finality.

Lou Lamoriello, the Islanders’ president and general manager, fired Trotz as coach on Monday after the team failed to make the playoffs, saying it was time for a “new voice.”

“It would be a tremendous understatement to say that this wasn’t an easy decision to make,” Lamoriello said on a conference call with reporters. “This is a business decision as far as hockey and winning.”

Lamoriello has made 21 coaching changes since he was named general manager of the Devils in 1987 and has not been shy about exchanging one big-name coach for another. He would not say what his plans were for a new leader behind the bench, but in explaining the surprising move, he made it clear he wanted more out of the current squad.

“What we need to do is get improvement out of our younger players,” he said, “and a more complete year out of some of our veterans than we did this year.”

Trotz joined the Islanders in 2018, just months after he led the Washington Capitals to the Stanley Cup championship. In four years with the Islanders, he compiled a 152-102 won-lost record with playoff appearances in his first three seasons, including trips to the conference finals in 2020 and 2021.

After an impressive run to Game 7 of last year’s conference finals against the eventual champions, the Tampa Bay Lightning, the Islanders seemed poised to build on that performance and go even deeper. Instead, they endured a disastrous season that was stacked with obstacles from the outset.

They opened with 13 road games while they waited for construction on their new home, UBS Arena, to be completed, and won just five of those games. Then a lingering coronavirus outbreak sidelined key players for long stretches.

On the ice, they never fully recovered from their slow start. They played better in the second half of the season, but were around .500 for most of the year and finished 37-35-10 (84 points), good for fifth in the Metropolitan Division.

In 23 N.H.L. seasons as a head coach, Trotz has won 914 regular-season games, third most behind Scotty Bowman with 1,244 and Joel Quenneville with 969. He also won 83 playoff games and was named coach of the year twice, including after his first season with the Islanders when the team was 48-27-7 before losing to the Carolina Hurricanes in the second round of the playoffs.

“I would like to thank Barry for everything he’s done for the organization for the last four years,” Lamoriello said.