Kodai Senga of the Mets walks to the dugout after the third...

Kodai Senga of the Mets walks to the dugout after the third inning against the Miami Marlins at Citi Field last Sunday. Credit: Jim McIsaac

CINCINNATI — The Mets have spent the last few weeks going to extreme measures to solve their pitching woes, but perhaps none was as drastic as Friday’s, when they announced that Kodai Senga had accepted a demotion to Triple-A Syracuse — a result of the former ace’s struggles since returning from the injured list in July.

Senga’s contract gave him the option to deny the request, but “this was the right thing to do for the team and the player,” president of baseball operations David Stearns said.

“He wants to figure this out and we think getting him a little bit of time away from elite competition, away from the pressure of a playoff race, is the right thing to do.”

Manager Carlos Mendoza confirmed that righthander Brandon Sproat, the organization’s No. 5 prospect, will get the start against the Reds on Sunday. He’ll join fellow rookies Nolan McLean and Jonah Tong, who have been deployed in an attempt to save a rotation in shambles.

The Mets, who will remain with a six-man rotation, also are considering a piggyback situation, Stearns said — something that could benefit Sean Manaea, who’s routinely gotten into trouble the second or third time through the lineup, or Clay Holmes, who has far surpassed his career high in innings pitched.

The decisions are being made “series by series,” Stearns said, adding, “Could [we be using] tandems at some point? Sure. Then we’ll just see how we go the rest of September.”

Senga dominated early in the season before suffering a hamstring injury on June 12. He pitched to a 5.90 ERA in the nine games since his return. He’s openly struggled with his mechanics — potentially a result of compensating for the injury, Stearns said — and has experienced a downtick in velocity, greater inconsistency and decreased command.

Still, “[you have] so much respect for the player, but also a lot of respect for the person, for Kodai,” Mendoza said, referring to Senga accepting the assignment. “He was all on board. Obviously, [he’s] disappointed. He wants to be here. He wants to help us but he understands where he’s at physically, where we’re at as a team and where he’s at performance-wise.”

A return in late September or October isn’t guaranteed, either: Mendoza said Senga will start by throwing bullpen sessions and likely won’t get into a game for about a week. He also needs to stay down for a minimum of 15 days.

By the end of September, “I think we’ll know whether what’s coming out of his hand and the results are what we need to see going into October,” Stearns said.

Until then, they have to hope that McLean and Tong can build on their early success and that Sproat can rise to the challenge.

The Mets also lost Frankie Montas and Griffin Canning to season-ending injuries, but not before they tried to get a struggling Montas right by relegating him to the bullpen.

“We’re asking a lot of young players, of players who haven’t done it at the big-league level yet, but also players who are really talented and we believe are ready for this challenge,” Stearns said. “We’re excited for them. I think we’ve already seen Nolan and Jonah meet that challenge and we expect Brandon to do the same.”

The Mets also added righthander Wander Suero to the active roster Friday. He was claimed off waivers Thursday after Atlanta designated the reliever for assignment earlier this week.

Alvarez returns

Francisco Alvarez was reinstated from the injured list despite a torn UCL in his right thumb and a broken pinkie on his left hand. Hayden Senger was optioned in a corresponding move.

Though Alvarez said he feels no pain, he, Mendoza and Stearns acknowledged the situation is fluid.

Alvarez’s UCL tear appeared to be season-ending, but “a few days [after that], he’s taking swings, full go,” Mendoza said. “And then he goes down there [to Triple-A] and the first [rehab] game, he gets hit and he’s got a fracture, and not two days later, he’s swinging the bat again. It’s unbelievable.”

Alvarez said he just feels tightness in the pinkie and senses slight instability in his thumb when throwing but added that he is learning to adapt to a new motion.

A tough start to his season — partially caused by the broken hamate bone he suffered in spring training — resulted in Alvarez getting demoted in June, but he’d been on a tear since coming back to the big leagues, slashing .323/.408/.645 with four homers and 13 RBIs in 21 games.

“I don’t have time to think about [playing through the pain],” Alvarez said. “I just keep thinking about playing and winning and it’s the only two things going through my head.”

Even if he’s able to finish out the season, the catcher will need surgery.

“I give him a ton of credit for doing this because he could have very easily come to us a day after he suffered the injury in Williamsport and said, can you give me the surgery?” Stearns said. “He did the exact opposite. He said, whatever I need to do to keep playing this year is what I want to do ... I’d be lying if I said I knew exactly how this was going to play out. This is an injury and it’s always tough to know exactly how this is going to progress.”

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