There was some back-and-forth between Francisco Alvarez and Andy Pages, who crossed home plate after his first home run and exchanged words with the Mets catcher.

In the immediate aftermath, it was unclear what was said. More clear was that, amid a quiet postseason, it was not just Alvarez’s mouth that spoke up Friday.

The previously slumping Alvarez carried a loud bat that woke up just in time, coming through with three hits that included a key double and RBI single in the Mets’ survival of a 12-6, Game 5 win over the Dodgers at Citi Field, which sent the NLCS back to Los Angeles.

Alvarez has been among the most scrutinized Mets in what had been a postseason to forget.

The 22-year-old was consistently flailing in large and small moments alike, going 5-for-35 with one walk, 13 strikeouts and no extra-base hits in his first 10 postseason games.

The catcher has appeared to bring his roller-coaster regular season into October, and he’s suddenly riding the highs: After five hits in 10 games, he has recorded four hits in his past two games.

“I know when you’re struggling, you’ve got a lot of people in your ears and you ‘need to do this, need to do that,’ ” manager Carlos Mendoza said after Alvarez’s 3-for-4 night. “Especially this time of the year, the simpler the better. That’s what he did. Just trying to stay short to the ball, see the ball.”

A former stud prospect who rose through the system as a bat-first catcher is now showing off that bat at the highest level.

Alvarez sprayed the ball around in rewarding the faith that Mendoza has shown in him.

Mendoza repeatedly has said Alvarez is his catcher and repeatedly has declined to give a look toward backup Luis Torrens, who has not started a postseason game.

That move looked smart when Alvarez smacked a double over right fielder Mookie Betts’ head in the second inning.

Alvarez would be stranded at third in the frame, his teammates doing what he has done too often this postseason in failing in the clutch.

He atoned in the next inning.

With two outs and Starling Marte on third against Jack Flaherty, Alvarez hung with a second-pitch slider and slapped an RBI single through the left side. The clutch baton was passed, Francisco Lindor then cracking an RBI triple before Brandon Nimmo singled in another run.

“Not trying to swing too hard and just be short to the ball, be on time, and just basically relax,” Mendoza said of Alvarez, who Mendoza had said was trying to do too much earlier in the series.

Offense, Alvarez will tell you, is not his primary job. He whiffed on a foul pop from Max Muncy in the fifth inning, which mattered when Muncy walked and Pages drilled a three-run home run.

But otherwise, Alvarez did well to handle a pitching staff that danced out of enough trouble to guarantee a Game 6 — a game that Alvarez surely will start, this time without much controversy.

“I know it’s easy for me to sit here and say it, but he’s also doing it. He’s a really good player,” Mendoza said. “I’ve been saying it. And he’s showing it right now.”