MILWAUKEE – Pete Alonso reminded us all once again how fickle baseball can be, how a single hit can change a season, a team, a legacy and perhaps even the trajectory of an entire career.

“Pete! Pete! Pete!” shouted the people as Alonso walked through the spartan concourse in the bowels of American Family Field on his way to the postgame press conference, a celebration in itself. Of course, these were all close friends and family waiting outside the victorious clubhouse. But they might as well have been everyday Mets fans, whose opinions and views on the struggling but struggling Met certainly depend on a pitch, a strike and a point in time.

“It’s a really special moment,” Alonso said afterwards in his usual unobtrusive manner.

In fact, it’s quite possibly a life-changing moment.

Let’s face it: No owner, no matter how wealthy, is going to spend $158 million (what they offered last year, according to Joel Sherman) or more on a star who’s in September and October virtual power collar has taken over. Oh, Alonso scored here and there, he generally played airtight defense (a late foul notwithstanding), and dutifully reported to work every day, broken or not, just as he did throughout his entire 162-game record in regulation Season.

Oh, club owner Steve Cohen and his financiers (yes, even self-made billionaires have advisors) would have made some sort of perfunctory offer to Alonso if the Mets had been eliminated in the wild-card round with just a whimper from Alonso. But there would have been no excitement, no momentum and really no chance for Alonso to be back in a Mets jersey.

He seemed to be going, going, gone.

Now, after his wild-card winning home run in the final inning, the Mets and Alonso have something nice to talk about. The season was already a success, but with his mighty hitting, he transformed these never-dying Mets into the greatest, happiest story in sports. As they snuck into the playoffs, they qualified for a nice local story thanks to some cardiovascular comebacks in Game 161 and the first paper tiebreaker in baseball history (sorry D-backs).

Alonso made his Mets team national when he hit the 3-and-1 changeup from star Brewers closer Devin Williams over the right field wall, making the Mets the belle of that October ball and truly changing everything. Francisco Lindor’s home run off the Braves’ Pierce Johnson that made all of this possible was arguably the greatest home run in Mets history.

Now, three days later, Alonso has even surpassed his long-time teammate Lindor, the Met all-rounder and all-rounder who is their clear and obvious MVP. Alonso was supposed to be the second man, but he wasn’t even that this year. Oh, his numbers look okay. He hit 34 home runs. Somehow he managed an OPS-plus of 123, the exact same mark as last year.

But it all felt very empty. He never seemed to get any big hits. It was always young Mark Vientos or underrated, underpaid veteran Jose Iglesias or, of course, Lindor. Until the home run that left Brewers fans crying in their Miller beers, Alonso’s top five hits all came in the first half based on win probability.

That all changed when Williams tried to switch outside half with Lindor and Brandon Nimmo on base. Alonso’s eyes undoubtedly widened.

“Just one of those terrible matchups for Williams,” one scout said. “His best pitch is changeup. Alonso destroys change.”

Well, he just about made up for that win by turning a 2-0 deficit into a 3-2 lead in the ninth inning and immediately ignited the sold-out stadium. There was sadness in the park for the small team that is always a champion in the regular season but barely makes it in October.

(My theory: Milwaukee’s front office is smart enough to find enough bargains to dominate the little things that work over 162, but big and highly paid stars often win the day the playoffs begin.)

As for Pete, the slump is right there on his Baseball Reference page: no home runs since September 19th, not even an extra-base hit.

The slump became so evident that every time he came to bat, we in the press box said to each other, “Pete’s due.”

And now that he’s done what we’ve all been waiting for, it’s all in the past tense. He was due and he did it in style with his old swing that changed everything for the better.

Alonso doesn’t really acknowledge his mistakes or address them. (Maybe he thinks it’s bad luck?) But anyone could assume that this super talent must have applied pressure.

“Hopefully this will allow him to breathe out and relax a little, then maybe he’ll burst into tears,” a Met said afterwards, expressing what was on everyone’s mind.

A lot of good things happened for the Mets this year. Vientos became a true source of power. David Peterson, who saved the Mets’ biggest win in nine years, is a pitching star. If Pete is Pete again, who knows? They’ve already gone far beyond what almost anyone would have thought, but if Pete is Pete, who knows how far they can go?