The New York Islanders have been one of the surprise teams in the NHL this season, second in the Metropolitan Division, three points behind the Washington Capitals.

On Saturday the Islanders (46-26-7) clinched their first playoff berth since 2016 with a 5-1 win against the Buffalo Sabres.

Picked by most experts to miss the playoffs for a third straight season after center John Tavares left to sign a seven-year contract with the Toronto Maple Leafs on July 1, 2018, the Islanders rallied around each other and defied the odds.

"I don't think there was a lot of expectations on the Islanders; everybody thought we would fold," coach Barry Trotz said. "The people that are in the organization, be it the players, obviously the management and the structure, nobody felt that we couldn't be a pretty competitive team. I think the players' mindset is that people are underestimating us. We came in and said, 'let's have a really good team game,' and a team game makes up for a lot of things. … Everybody contributes, and that's the strength of our group."

Video: #ThirstForTheCup: Islanders clinch a playoff spot

Here are five reasons why the Islanders clinched a playoff berth:

1. Structure

The Islanders made massive changes after allowing a League-high 293 goals in 2017-18 and missing the playoffs for the eighth time in 12 seasons with Garth Snow as general manager.

Lou Lamoriello was hired as president of hockey operations on May 22, 2018, and he fired Snow and coach Doug Weight on June 5.

Trotz replaced Weight as coach on June 21, two weeks after delivering the Washington Capitals their first Stanley Cup championship. A defense-first system was implemented in training camp and has resulted in one of the more impressive turnarounds in recent memory; not only have the Islanders clinched a playoff berth, they've allowed the fewest goals in the NHL (188).

"It just feels right the way we play," Trotz said. "When you play right, it feels right and you don't really worry about the score as much. … Just play and then we can frustrate teams, we can get on you and the results sort of come."

2. Goaltending

Most playoff teams long ago established a pecking order for their two goalies, but the Islanders have split the duties right down the middle.

Robin Lehner, signed to a one-year contract on July 3, 2018, and Thomas Greiss, who had a 3.82 goals-against average and an .892 save percentage last season, has each started more than 35 games. Each is among the NHL leaders in goals-against average and save percentage. Each has five shutouts.

Video: BUF@NYI: Lehner stones Larsson in 3rd

It's the first time since the 1981-82 season (Billy Smith and Roland Melanson) the Islanders have had two goalies with at least 20 wins. Their 10 shutouts are the most in the NHL.

"You want to come in and give something back to the coaches when they give you the opportunity," Lehner said. "Both me and [Greiss] have been playing well, and everyone as a team. Whoever's in, it doesn't matter."

3. 'The identity line'

One of Lamoriello's first roster moves was to bring left wing Matt Martin back to New York after a two-year hiatus with the Toronto Maple Leafs.

Trotz wasted little time reuniting Martin with Casey Cizikas and Cal Clutterbuck, and the three barely missed a beat from the 2015-16 season and set the tone for the way the Islanders have needed to play to have success, so much so Trotz labeled them 'the identity line.'

New York is 33-15-6 when Cizikas, Martin and Clutterbuck all play, and 13-11-1 when one or more is unavailable.

"I think Matt and Cal and I, the way we play, we just read off each other so well," Cizikas said. "We have confidence in each other, and the trust we have in each other out there is special. When we're out there we're having fun, we're playing hard and we're doing what we have to do."

4. Leadership

Tavares' departure also left the Islanders without a captain, a position he held for six seasons. Trotz went all of training camp without naming a replacement, and there was talk the Islanders would play the season without one.

But on the morning of their season opener (Oct. 4, 2018 at the Carolina Hurricanes), left wing Anders Lee was named the 15th captain in Islanders history.

Video: NYI@WPG: Lee tips home Pulock's one-timer for PPG

"He's done a terrific job," Trotz said. "It's not the easiest situation coming in [and replacing Tavares]. I think he's been Anders Lee; he's just been himself.

"He's adjusted really well. He's a symbol of Islander hockey."

Lee has had help in the leadership department; veterans such as Josh Bailey, Andrew Ladd and Johnny Boychuk remain in the mix, but the additions of center Valtteri Filppula and forward Leo Komarov as unrestricted free agents have proven to be invaluable on and off the ice.

Filppula sustained an upper-body injury on March 19 but could return towards the end of the Eastern Conference First Round.

5. Progress of young defensemen

The Islanders haven't received much offense from their defensemen (none reached double digits in goals), but they have certainly been steady in their own end. What's more impressive is how they've done so without much experience.

Ryan Pulock and Adam Pelech, each 24, are in their second full NHL seasons. Scott Mayfield, 26, played 47 games with the Islanders last season. Devon Toews, 25, made his NHL debut on Dec. 23, 2018, and hasn't looked back.

One could make a strong case the Islanders haven't been this deep on defense in years when you include Boychuk, Nick Leddy and Thomas Hickey. Luca Sbisa, who helped the Vegas Golden Knights reach the Stanley Cup Final last season, has been a healthy scratch since Jan. 12.

"This is the time of year when you need more bodies," Hickey said.