Mets starting pitcher Sean Manaea celebrates with teammates in the...

Mets starting pitcher Sean Manaea celebrates with teammates in the dugout after the seventh inning of a game against the White Sox in Chicago on Sunday. Credit: Nam Y. Huh

At 32 years old, in his ninth season in the majors and with his fourth team, Sean Manaea is doing the best pitching of his life.

Over the past month-plus, Manaea has been one of the biggest reasons for the Mets’ continued playoff push, not only suppressing scoring (2.42 ERA) but also offering length that in turn bolsters the bullpen (completing seven innings in five of seven outings). Nothing else Manaea has experienced compares to this run, he said.

And the Mets need him to keep going, keep doing exactly this. Their postseason fate might depend on it.

“I’ve been feeling really good with mechanics and my pitches, results — everything has been really good,” Manaea said ahead of his start Friday against the Reds. “So it’s definitely the best of my big-league career.”

The Mets need to finish ahead of at least one of Atlanta, Arizona and San Diego to snag a National League wild-card spot. Upping the importance of Manaea’s top form: Their margin for error, thin generally, is perhaps thinner specifically with the rotation, where they lack bona fide front-end pitchers.

The five starters constituting this version of the rotation have enjoyed something close to a best-case scenario for their respective seasons. If a couple of those spots become shaky down the stretch, they could take down the Mets’ relevancy with them.

Consider:

* Luis Severino has stayed healthy the entire season and flashed the early-career dominance that made him a star with the Yankees. This has been by far his biggest workload since 2018. Even with overall average-ish results — 3.84 ERA, 1.26 WHIP — that he has pitched this well for this long represents a huge win for the Mets.

* David Peterson has been fascinatingly successful since returning in May from offseason hip surgery. With a 2.75 ERA — including a 1.81 mark in seven starts during the same period of Manaea’s surge — he has surprised and impressed Mets decision-makers, consistently outperforming his expected/underlying statistics. They wouldn’t be surprised if he regresses but they hope he can hold on for the rest of the month.

* Jose Quintana functioning as a serviceable back-end arm — with spurts of being more — also counts as a victory. His dud potential in any given start is higher than the others, but he usually avoids a total mess.

* Paul Blackburn has been a decent supplement since joining the team at the trade deadline, contributing three high-quality starts and two messes in his five outings. He is due to return next week in Toronto after missing two starts because of a bruised right hand.

Given the various degrees of uncertainty with the others, Manaea maintaining his suddenly higher standard is key. The Mets unexpectedly have come to rely on him, with manager Carlos Mendoza recently referring to him as the team’s No. 1 starter — a would-be Game 1 starter in the playoffs, if the Mets are able to line that up the way they want.

Manaea’s improvement stemmed from a significant change to his delivery in late July. Watching Atlanta’s Chris Sale, the potential NL Cy Young Award winner, Manaea noted his unorthodox cross-body motion featuring a lower arm slot than Manaea had long used.

As a similarly tall lefthander, Manaea decided to give it a go in his next appearance. And . . . it went great, so much so that Manaea is a virtual lock to opt out of his contract for 2025 and test free agency again this offseason.

That sort of in-season more-than-a-tweak is rare.

“It’s pretty difficult. What he’s doing is pretty remarkable,” pitching coach Jeremy Hefner said. “It speaks to his athleticism and his willingness to try. The worst thing that could happen is he pitches like he always has, and he’s a pretty good major-league pitcher, right? But there’s some chance he could do what he’s doing. Credit to him for wanting to go down that path.”

The Mets were skeptical at the time, but it worked. They need it to keep working with just 22 games to go — five of them likely started by Manaea.

“This is what you dream of and what you play for,” Manaea said. “The playoffs have pretty much already started in my eyes.”

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