ATLANTA -- The Mets will be without their ace for quite a while yet.

The team on Wednesday transferred Kodai Senga from the 15- to the 60-day injured list to clear 40-man roster space for Tyler Jay, a reliever they called to the active roster. Senga, who recently began throwing off flat ground during his rehab from a strained posterior capsule in his right shoulder, is not eligible to return from the IL until May 27.

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“From the beginning, we knew it was going to take time,” Mets manager Carlos Mendoza said. “We’ve been slow playing it from the beginning. We took that extra couple of weeks before he started playing catch in Spring Training. There’s nothing new to it. It’s just more where we’re at, where he’s at.”

The benefit of shifting a player from the 15- to the 60-day IL is that Senga no longer counts against the 40-man roster limit.

Senga, 31, has been sidelined since early Spring Training due to a shoulder capsule strain. He went about a month without throwing at all before graduating to a flat-ground throwing program in late March. But Senga has yet to throw off a mound. Even once he does, he will need to progress through a series of bullpen sessions, live BP sessions and eventually game action. The Mets also intend to space out Senga’s rehab starts, regularly giving him an extra day of rest.

“Not a setback. Nothing wrong with him,” Mendoza said. “We just knew it was going to take some time. With him still throwing flat grounds and things like that -- he hasn’t even gotten on a mound -- it’s going to be a few weeks before we see him. So that was the move.”

Although Senga is eligible to return on May 27, no guarantees exist that he will do so at that time. Much will depend upon the speed of his rehab process.

“It’s too early to tell,” Mendoza said. “He still hasn’t even touched the mound. We still have to clear some hurdles here.”

The team’s best pitcher last year, Senga went 12-7 with a 2.98 ERA and 202 strikeouts during his first season in the big leagues. Prior to that, he was an ace pitcher over 11 seasons in Japan, earning himself a five-year, $75 million contract with New York in 2022. Of note, Senga can opt out of his contract following the '25 season if he accumulates at least 233 2/3 innings before that time.