Yoenis Cespedes has been part of the problem for the Mets this year, mainly by being injured and unavailable again.

Of all things, he may have proposed a way to be part of a solution moving forward — for his own health and the structure of the team.

According to a source familiar with the issue, it was the slugger who broached the idea of him playing at least some first base. As part of the baseball activities he is doing now more regularly in Port St. Lucie, Cespedes is not only taking fly balls in left, but grounders at first.

Cespedes played some third base while still in Cuba and — when healthy and active — often takes grounders at third during batting practice. The source said he actually loves taking grounders and that he sees moving to first base at least part of the time as a way to lessen the strain on his perpetually injured legs. Cespedes is on the DL with quad and hip flexor ailments.

Assistant GM John Ricco, in a phone conversation, said he did not remember the sequence of events that led to the consideration of Cespedes at first. But he did say Cespedes has more than willingly embraced the possibilities.

“We know he is open to the idea,” Ricco said. “That is something we have to discuss long term if that works. He is taking grounders to see how it feels. That is the extent of it so far. We hope to have him in rehab games during the All-Star break. We still anticipate that he comes back as an outfielder. But we have had discussions, and he is open to first base.”

The source said he would be surprised if Cespedes did not play some first for the Mets this year and Ricco offered: “There is a chance we do that. It is kind of the early stages of how he looks out there. You would love to have spring training to get ready. But if he has the aptitude for it and guys [the coaches] feel he can do it, you may see him over there.”

Of course, first Cespedes has to get and stay healthy and then show he is committed to prioritizing what is best for the team — left field or first base — because he has balked at playing center or right, even when he was the most physically qualified Met to do so.

But if Cespedes can handle first, he can help address the Mets having too many corner outfielders, poor center-field defense with Michael Conforto or Brandon Nimmo force-fed into the position and too few scary bats in their lineup.

Sandy Alderson had said that one reason the Mets signed Jay Bruce to a three-year, $39 million contract is he could move to first if needed. But Bruce is hurt, in the midst of a bad season and has played first upon request, but has never expressed great happiness when shifted there. Cespedes, at least for now, is giving the Mets the vibe that he would be a willing pupil in trying this.

The Mets, despite a second straight miserable season, are proceeding with the idea of trying to win again next year. So, if Cespedes can handle first, then he, Bruce, Conforto and Nimmo could play simultaneously to try to upgrade the offense, albeit while still giving up center-field defense. In addition, it would lessen by one the corner-outfield bulk, and the Mets can always try after July 31 (because he would almost certainly get through waivers) or in the offseason to trade Bruce by eating some money and/or taking on a contract, and then see if Juan Lagares can ever stay healthy enough to man center full time — or find a legitimate center fielder such as A.J. Pollock on the free-agent market.

If Cespedes could grab first base regularly, it would block Dominic Smith and Peter Alonso. But the Mets have proceeded as if Smith has lost luster already while — after tearing up Double-A — Alonso has struggled in his initial Triple-A foray, plus outside talent evaluators question if he will have the athleticism to succeed as a major league full-timer.

First things first, though, is Cespedes actually has to show he can handle the position.