The outcomes of the Mets’ games no longer matter. What might matter, though, is David Peterson rediscovering his best pitch.

Among the quieter and at the same time bigger disappointments this season has been Peterson, who was invaluable in 2022 as a pitcher who jumped in and out of the rotation, often excelling with a slider that no one could touch.

This season, Peterson lost his best offering, which helped lead to his losing too many games and then losing his major league spot.

As he tries to find himself in the final weeks of a lost season, Peterson might have found his best pitch again, and it was on display during a 5-3 loss to the Reds at Citi Field on Friday.

Cincinnati batters swung at his slider eight times, and they missed eight times.

Peterson threw 12 sliders in total: One was a called strike, three were balls and zero were put in play.

“[The slider] obviously hurt me in the beginning of the year, and we had to make some changes,” said Peterson, who now holds his hands higher in his delivery. “Feels good to have that pitch back.”

Peterson allowed three runs (two earned) in 5 ²/₃ innings in which he let up six hits and walked two.

He also tied a career high with 10 strikeouts, predominantly with a pitch that started as a strike and then kept sliding out of the zone.

His issues for the night centered on two other pitches: a too-high fastball that went as a wild pitch and allowed the Reds to score their first run, and a first-pitch changeup to his former University of Oregon teammate Spencer Steer, who hammered a two-run homer.

Peterson’s biggest weapon, though, was devastating.

Last year, Peterson’s slider induced a swing and miss 47.9 percent of the time. Among pitchers with at least 50 plate appearances against, that whiff rate was the 32nd best of any pitch in baseball.

This year, that percentage was down to 38.5 entering Friday.

Last season, hitters batted .175 against the slider. Entering Friday, opponents were hitting .297 this year against it.

If the lefty can bring the rediscovery into next season, the back of the Mets’ rotation would look a lot stronger.

“I think it’d be big,” Peterson said about finishing the season strong. “You want to go home with a very productive mindset as to how we finished the year. Obviously things have not gone our way. But … you got to take the progress as much as you can into the offseason and continue to work and come back and be ready to fight.”

Brett Baty was scheduled to hit and throw on Friday, but his return to the Mets’ lineup likely isn’t to occur before he starts running again.

The rookie third baseman is nursing a left groin strain, but avoided the injured list after he left the game Wednesday in discomfort.

Baty said the groin had bothered him for about a week, but it wasn’t until he stopped abruptly while rounding second base on Wednesday that he became concerned.

“It was a good sign with the imaging,” Baty said. “We thought it might be something else, but it was good.”

Ronny Mauricio got the start at third base in Baty’s spot.

The Mets’ success against the NL wild-card contenders hasn’t been lost on manager Buck Showalter.

After the loss Friday, the Mets are 23-14 against the top six teams in the NL wild-card standings.

That included winning three of four games against the Diamondbacks to begin this homestand.

“Our starting pitching has been better,” Showalter said. “It’s been pretty fairly consistent. We have been running out some good starts for a while now.”

Edwin Diaz will continue traveling with the Mets, accompanying the team to Miami and Philadelphia on the next road trip, according to Showalter.

On Monday, the All-Star closer is scheduled to throw off a mound at the team’s spring training complex in Port St. Lucie, where he likely will receive biomechanical analysis in the organization’s new pitching lab.

Diaz is rehabbing from March surgery to repair the patellar tendon in his right knee and the possibility of his return in the regular season hasn’t been ruled out.

Starling Marte is also scheduled to travel with the Mets.

The veteran outfielder is rehabbing from a right groin strain that has kept him sidelined for the past six weeks.