NEW YORK — If this was indeed a farewell, Pete Alonso went out with a bang.

Over the past six seasons, Flushing’s first baseman has delivered memory after memory for the adoring patrons of Citi Field. Set to become a free agent whenever the Mets’ storybook season draws to a close, Alonso has been understandably noncommittal about his future. A loss on Friday would have, perhaps, signaled the end of a magnificent run for a magnificent player.

But Alonso and his indomitable Mets wouldn’t go down that easily.

In the bottom of the first inning of Game 5 of the NLCS, Alonso scooped a Jack Flaherty curveball well below the strike zone and sent it rocketing toward the Big Apple in center. As a desperate Citi Field rose to its feet, the man of the hour admired his handiwork, strolling down the baseline before hucking his bat to the heavens about 10 feet from first base. It was Alonso’s fourth long ball of this postseason and the 106th of his career to come at Citi Field, far and away the most in the stadium’s history.

That swing started a party, perhaps the last of many in what has been an unforgettable year in Queens. New York took Game 5 over the Dodgers 12-6. Their season, for now, is still breathing. Yet the odds remain long as the series heads west, with the Dodgers still up three games to two. If the Mets want to play another game at home this season, they’ll need to conjure two more improbable performances in L.A.

Alonso, with an early swing, offered Mets fans the chance to dream.

“Pete with a big one to set the tone,” Mets skipper Carlos Mendoza said in his postgame media conference. “We needed it today [and] to continue to add on because we saw it — they’re not going to shut down. They’re going to continue to put pressure on you. That’s a really good offense there. I’m proud of the guys. Definitely Pete, a big one in the first inning.”

Moments after his opening salvo, Alonso journeyed through a tunnel of atta boys and butt slaps toward the far end of the home dugout. There, he engaged in the team’s customary home run celebration: a picture with José Iglesias’ enormous plastic OMG sign. Per tradition, the homering hero is joined by anyone else who scored on the play. In this case, it was Brandon Nimmo and Francisco Lindor, the other two most prominent Mets hitters during Alonso’s tenure.

The three posed, their arms draped around one another, toothy grins stretched across their faces. It’s the type of photo that — whether or not the Polar Bear returns to Queens — should one day find its way into a frame and onto a wall in the Alonso home.

Whenever the Mets’ magical run concludes, be it in Los Angeles or beyond, Alonso will become a free agent. His platform year was not, by his standards, a strong one. His .788 OPS and 34 home runs were both the lowest full-season marks of his career. But he has shined in October, with an OPS of .990 and a highlight reel of clutch swings. Whether that makes a difference this offseason remains to be seen.

The Tampa-raised slugger is important here now, in this unforgiving metropolis. He matters to this franchise and fan base. But bestowing a nine-figure contract upon a power-centric first baseman with iffy athleticism set to turn 30 in December is a risky play outside the modus operandi of Mets president of baseball operations David Stearns.

The future for Alonso is hazy. But predictably, he’s focused on the present. When asked if he thought about the fact that Friday might’ve been his last home game as a Met, he answered with a quick “no.”

“I was just pretty much focused on competing and trying to win and get this thing to Game 6 and contribute however I could to help the team win,” he said. “That’s pretty much it. That’s what this postseason is about: It’s about winning. It’s about surviving and living to see another day until there’s no more baseball left.”

Alonso is an interesting figure, one whom some around the league find corny, overeager, uncomfortably earnest. The image of him doing deep breaths before a losing effort in the 2022 Home Run Derby only furthered that reputation. But within his own clubhouse, Alonso is well-liked and respected for who he is. In a sport that features countless players with a too-cool-for-school attitude, Alonso does not shy away from showing how much he cares. And the same traits that rub some the wrong way endear him to the people with whom he spends the most time.

“He was quirky,” a former teammate told Yahoo Sports. “But, like, that’s who he is. It’s 100 percent genuine. I’d ride for him.”

The Mets slugger does not float through life with the suave of Francisco Lindor or the effortlessness of David Wright. He moves clunkily, like somebody trying to run with a heavy backpack and pockets full of pennies. His many post-home-run jaunts around the bases are more toddles than trots. A different former teammate once described him as a golden retriever who just wants to be played with.

But while nobody would describe Alonso as cool, what he’s able to conjure with his immense baseballing talent is downright polar. That’s what happened, once again, on Friday.

Alonso’s fire-starting shot was only the beginning of a high-scoring, poorly pitched slugfest. New York broke the game open early against Dodgers starter Flaherty. The Souther California-raised right-hander was magnificent for L.A. in Game 1, turning in seven scoreless. But in Game 5, he was a fizzless soda, a pitching machine in a uniform. Flaherty’s fastball was down nearly two ticks compared to his season average, and none of his secondary offerings were sharp.

The Mets took advantage in a five-run third inning, rapping out four hits and drawing two free passes on their way to an 8-1 lead. Citi Field, which has had precious little to roar about in this series, delighted in the drubbing.

Los Angeles battled back into the game in the middle innings on a three-run crank from rookie Andy Pages, his second of the game, that narrowed the deficit to five. A comeback lurked, forcing the Mets to call on their second-best relief option, flamethrower Ryne Stanek. The wavy-haired right-hander delivered the performance of his career, pitching 2 1/3 innings, the most he has ever thrown in a single outing, to keep the game in check. Closer Edwin Díaz also pushed past his typical limit, tallying the final six outs to close out a relieving Mets victory.

Thanks to Dodgers bulk reliever Brent Honeywell, who sponged up 4 2/3 innings after Flaherty’s early departure, the L.A. bullpen is set up fantastically for Games 6 and 7. The Mets, on the other hand, emptied their chamber to win Game 5, getting six outs from Díaz and seven from Stanek. Both of those high-leverage arms will be available and involved the rest of the way, but they could be less effective given their recent workload. This series, as it heads back to the west coast, remains firmly in L.A.’s hands.

But the Mets, at the very least, have made this thing interesting, which should be no surprise. While they might not return to Citi Field this year, this thrill ride of a team provided 43,841 souls with one more unforgettable evening under the lights in Queens.

And Alonso, who has lit up this place more times than anyone else, was the coolest man in the building.