The win marked the Islanders' first sweep since 1983 and just their second series victory over the last 25 seasons.
New York stifled the Penguins with its physical play from the start of Game 1 and received excellent goaltending from likely Vezina Trophy candidate Robin Lehner, who posted a .956 save percentage for the series.
The Islanders managed to control the middle of the ice, smothering the Penguins' attack and ultimately nullifying the impact of their star-studded forward group. Through four games, Pittsburgh's core four of Sidney Crosby, Evgeni Malkin, Phil Kessel, and Jake Guentzel combined for just three goals and seven points.
"We didn't execute well and made a few more mistakes than they did. Personally, I've got to be better," Crosby said following the loss. "It's disappointing for how well we finished the year and the things we played through to get into this position."
Though Penguins head coach Mike Sullivan wasn't upset by his team's overall effort, he pinned their downfall on a failure to execute in key situations.
"When you look at the nature of the games and the way they were played, it was a whole lot closer than the optics," Sullivan said, according to wtae.com's Andrew Stockey. "Every game, for that matter, was a one-goal game ... it boils down to critical moments."
Kessel, who has 303 points over four regular seasons in Pittsburgh, has been in mentioned in previous trade speculation and was asked about his future with the club after the loss.
"That’s a tough question to start," Kessel said, according to Jason Mackey of the Pittsburgh Post-Gazette. "I don't know at this point. We'll see how it goes this summer."
It's the second time the Penguins have been swept in the Crosby-Malkin era after falling to the Boston Bruins in four games in the 2013 Eastern Conference Final.