The deafening roar of 12,000 fans at Nassau Coliseum as first star Mathew Barzal skated out of the tunnel late Saturday night before pointing to the ice and yelling “Our house!” following his terrific all-around performance in the Islanders’ 4-1 victory over the Bruins in Game 4 of a second round series sure felt like the first post-dynasty moment authored by a franchise player beginning the process of lifting himself and his team to those long-sought heights.

Of course, many — maybe even most — of those 12,000 fans were also in attendance 30 or so miles to the west on Apr. 24, 2016, when John Tavares did his part to complete what amounted to a 2-on-18 elimination of the Panthers by scoring in the final minute of regulation to force overtime before he collected the series-winning goal in double overtime of a 2-1 win in Game 6 at Barclays Center that gave the Islanders their first playoff series victory in 23 years.

“The only way to put it is he took us all, put us on his back and decided he wasn’t going to lose,” Islanders right winger Cal Clutterbuck said of Tavares, who scored five of his team’s 15 goals in the series.

But, well, it’s complicated with Tavares, whose awkwardly handled departure for his hometown Maple Leafs two summers later infuriated fans far more than the inability of first-round picks Ziggy Palffy, Todd Bertuzzi, Roberto Luongo or Rick DiPietro and big-ticket acquisitions such as Alexei Yashin, Trevor Linden or Michael Peca to rouse the Islanders out of their decades-long malaise.

So it’s understandable if Islanders fans want to identify Barzal’s emotionally charged two-point evening as the game they’ve been waiting to see from a superstar for going on two generations, even if it only helped the Islanders tie a best-of-seven series instead of winning it.

But it’s also much closer to a defining game for the player and the franchise than Tavares’ series-winner was five years ago.

“It’s fun to watch — he’s an elite player with superstar skills, and when he’s going out there we’re following right behind,” said Casey Cizikas, one of seven active Islanders remaining from the 2015-16 team. “He’s getting the puck in deep. He’s not turning it over and he’s making stuff happen.”

For most of his first four NHL seasons, the absurdly talented center — his overtime shifts should be on pay-per-view — was prone to freelancing and displaying flashes of immaturity that would likely be rationalized by most teams as acceptable growing pains for someone not even old enough to rent a car.

But nobody demands adherence to the system quite like the Islanders management team of general manager Lou Lamoriello and head coach Barry Trotz, the latter of whom scratched Barzal — who’d played in 314 straight games, counting the playoffs, since the start of the 2017-18 season — May 4 following a 14-game stretch in which Barzal had more penalty minutes (10) than points (seven) while registering a plus/minus of negative-2.

Barzal had back-to-back two-point games in the Islanders’ final two regular season tilts before being limited to four points in the first eight playoff games. Following a 5-2 loss to the Bruins in Game 1 on May 29, Trotz said the Islanders have “…got some guys who need to raise their games if we’re going to beat the Boston Bruins.”

Barzal’s did that over the two games at the Coliseum. In Game 3 last Thursday, he forced overtime by grinding out his first goal of the playoffs late in the third period, when he raced behind the net in pursuit of a puck fired off the back boards by Kyle Palmieri. Barzal corraled the puck and had two wraparounds turned back by Tuukka Rask before he finally poked home the third attempt.

On Saturday, Barzal created Palmieri’s game-tying goal in the second off a lengthy battle deep in the Islanders zone with Curtis Lazar. The Bruins’ center chased Barzal and tried poking the puck free during two pursuits between the top and bottom of the right faceoff circle before Barzal finally shook Lazar, headed to the back of the net and fired a pass to Palmieri, who fired a shot under the stick of a surprised Rask.

Less than five minutes later, Barzal was speared in the, umm, most sensitive of spots following a lengthy stick-shoving match with David Krejci. But Barzal returned to the ice before the end of the power play.

Barzal’s instinctual skill helped put the Islanders ahead with 6:57 left, when he passed to Scott Mayfield from the left faceoff circle but followed the play and was positioned to bat out of the air the puck when Mayfield’s bounced off the stick of Charlie McAvoy.

“i thought he was competing — as I use the term, he was fighting for his inches, he made some plays,” Trotz said of Barzal. “I like Mat’s game. He was dangerous all night and he kept putting pucks to the net and creating.”

The two games at the Coliseum marked the third time Barzal has scored in back-to-back playoff contests but the first time he’s done so with a positive plus/minus.

“It’s the playoffs — much as I’d love to produce every night, it’s so tight out there and sometimes just doesn’t come that easy,” Barzal said. “It’s more so just when it’s not coming offensively that night, it’s just making sure I’m not on the ice for any goals against or making that block or just trying to get the puck out and just playing sound hockey. A lot of shifts are just 50/50 and you’ve just got to grind it out. When things aren’t going my way in the playoffs offensively, that’s really what it comes down to: Just battling for the boys.”

The adaptation of Barzal arrives as the Islanders have begun forcing the Bruins — who averaged 3.41 goals a game in their first 22 games, counting the playoffs, following the trade deadline acquisition of Taylor Hall after averaging 2.79 goals per game prior to Hall’s arrival — to adapt to their sludgy style instead of vice versa.

The Islanders had just seven shots during a fight-filled scoreless first, which included Mayfield trading blows with Hall in the latter’s first fight in more than a decade.

“Good for him, I know he’s not known for doing that," Mayfield said. “That’s part of the game and it was a good little fight there.”

But the Islanders outshot the Bruins 13-8 during a clean, mostly whistle-free back-and-forth third and limited them to one shot after Barzal’s go-ahead goal and none in the final 6:18.

Afterward, the Bruins, who have played 62 postseason games since the spring of 2017 and are just two years removed from getting to the seventh game of the Stanley Cup Finals against the Blues, were complaining about the Islanders’ power play advantage thus far. The Islanders have been whistled for 13 penalties in the series, two fewer than the Bruins.

Regardless of how the Islanders fare the rest of this late spring and/or early summer — Game 5 against the Bruins is scheduled for tonight in Boston — there doesn’t seem to be anything fluky or fortunate about their third straight trip beyond the first round.

In the 2016 series against the Panthers, the Islanders won despite leading for just 45 minutes and 54 seconds and even though Tavares and Frans Nielsen were the only players with more than one goal. Thomas Greiss had the series of his career by stopping all but 13 of the 234 shots he faced.

The Islanders won the opener of the conference semifinals against the Lightning before losing the next four, a span in which they led for just 32 minutes and 57 seconds. It ended up being the final playoff series on the Island in the Tavares era.

Five years later, Barzal is still just 24 and completing the first year of a three-year deal that will leave him a restricted free agent again in the summer of 2023. Once prone to appearing sullen in public settings — hey, he’s in his early 20s — the visceral reactions Saturday were the actions of someone growing more comfortable as the face of a franchise, on and off the ice. As Saturday night proved, Barzal isn’t going anywhere, and neither are the Islanders. 

“We know who we are,” Trotz said. “We don’t try to be someone else or someone that you want us to be. We know who we are as a group and how we can be successful. It’s roster construction and we have some good pieces and they know their roles and they know their identity.”

Including, most importantly, the franchise player who might be the one able to lift the Islanders to long-ago heights.