David Peterson and Sean Manaea are swapping undefined roles, which says plenty about the state of the Mets.

It’s inaccurate to say that Manaea is taking Peterson’s spot in the starting rotation because the Mets are still tinkering with multiple “openers,” but Peterson was told Friday to be available out of the bullpen as soon as Sunday. Manaea could join the rotation or follow an opener next time out.

“As of right now, that’s kind of like the plan here with [Peterson] in a lot of different roles — multi-inning guy, high leverage against a good pocket for him, bulk guy,” manager Carlos Mendoza said.

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The Mets continue to tinker with Peterson (5.57 ERA) in hopes of righting his season. He already went from starter to pitching after an opener back to starter, and would have been in line to pitch Monday against the Mariners.

“That’s the decision that’s been made,” Peterson told The Post’s Jon Heyman. “My goal is to be ready to take the ball whenever it’s given to me and go do my job. That’s all I can really control. The rest is kind of out of my hands.”

What has gone so awry?

“It’s hard to pinpoint just one thing,” Mendoza said. “It’s been a combination of him missing arm slot at times, not executing glove-side, pitch selection at times. He’s still a very good pitcher.”

Mendoza stressed to Peterson that the situation is fluid, his is “an important role” and more opportunities will come based on performance. He described Peterson’s reaction as “professional.”

“I felt like we cleaned some things up after the slow start and I was out of whack mechanically last start,” Peterson said. “You never know [what’s ahead]. I feel like it’s kind of been week to week. This week, we’re out there [in the bullpen].”

Manaea, who was the Mets’ ace in 2024, has worked exclusively in relief (5.56 ERA) this season. He has pitched to a 3.75 ERA in May.

“Sean could be after opener,” Mendoza said, “but we want to give him a chance here, too, to be that bulk guy.”

The Mets are optioning right-hander Tobias Myers to Triple-A in order to get a fresh arm this weekend after using seven pitchers in Friday’s win, according to The Athletic. Myers served up a game-tying two-run homer to the Marlins’ Owen Caissie in the eighth inning. He’s struggled in May with a 6.43 ERA across 11 appearances.

Jorge Polanco (Achilles bursitis/wrist) could rejoin the Mets on their June 1-7 road trip. He batted leadoff at Double-A on Friday.

The plan calls for Polanco to play Saturday, sit Sunday and get back in a minor league lineup next week and then take it day by day.

“We seem to be trending positively with Jorge,” general manager David Stearns said.

Polanco told reporters in Binghamton’s dugout that he is “feeling way better,” but “there is no rush (because) I want to get back when I feel good.”

Jonah Tong, who pitched 3 ²/₃ innings of relief Wednesday, will be available out of the bullpen in “two or three more days.” He could start or follow an opener depending on the shape of the bullpen and the matchups atop the opposing lineup, according to Mendoza.

“He’s going to be another guy who is going to get outs for us,” Mendoza said.

Polanco could return to the Mets as soon as next week, which is the same timeline that Francisco Alvarez (knee surgery) could begin a minor league rehab.

Francisco Lindor (left calf strain) has resumed baseball activities (no timetable for return), but Luis Robert Jr. (series of injections on herniated disc) has not. Kodai Senga was knocked around in a rehab start at Triple-A on Thursday.