WASHINGTON — Jose Reyes pitched about as effectively as he has hit and fielded this year.

A historic 25-4 loss to the Nationals for the Mets on Tuesday night — the worst loss by run differential in their 57-year history — wrapped up on an appropriately ghoulish note at Nationals Park when Reyes, the longtime Met, took the mound for the bottom of the eighth inning and got knocked around for six runs, including two homers. The 35-year-old threw an astounding 48 pitches to get through his professional pitching debut, leaving with his career ERA of 54.00.

“When you’re on the mound, before you throw a pitch, it’s fun,” Reyes said. “But when you start to see people hit a homer and stuff, then you get more serious.”

The Mets used six pitchers to get through the first seven innings, and it was in the sixth inning, manager Mickey Callaway said, when he approached Reyes about pitching. With Noah Syndergaard returning from the disabled list to start Wednesday’s series finale, Callaway explained, he wanted to ensure he had enough relievers available. Hence the turn to Reyes, one of two remaining bench players (along with Devin Mesoraco) who hadn’t entered the game yet.

Besides, Reyes said, he had long wanted to pitch in a game. Last year, he patrolled center field in one game, achieving another career-long dream.

Using a quick, shot-putting delivery, Reyes alternated between a fastball that topped out at 87 mph and a curveball that bottomed out at 54 mph. That pitch hit Ryan Zimmerman, prompting the Nationals veteran to jokingly take a step toward the mound.

Matt Adams and Mark Reynolds clobbered homers off Reyes, and after the Nats batted around, pitching coach Dave Eiland went to the mound to check on Reyes. The Mets warmed up pitcher Paul Sewald as a precaution. Reyes recorded a third out, though, when Washington rookie Juan Soto flied out to Michael Conforto in left field. That finished a trying night in this very trying season for Reyes and his team.

“I’m glad that I got out of the inning and Mickey didn’t have to use another position player or pitcher,” said Reyes, who admitted peeking at the ballpark’s radar gun a few times.

Following his first mound appearance since he was a pre-teen, Reyes smiled at the question of whether he’d be available for Wednesday.

“Not to pitch,” he said.