Maybe instead of Noah Syndergaard, Tomas Nido should be Edwin Diaz’s personal catcher.

With the backup handling the shaky closer Saturday, he worked a scoreless ninth inning a night after another blowup.

Before the inning, Nido went out to the mound and told Diaz to trust him. In the 15-pitch frame, Diaz shook off Nido just once, which led to the Phillies’ lone hit of the inning in the Mets’ 6-5 victory at Citi Field.

“When he throws that fastball up in the zone, it’s hard to hit,” said Nido, who also drove in the game-winning runs with a three-run double in the fifth. “That’s how you start, just going out there and trusting your stuff. It’s what I thought was right for him.”

Nido called all fastballs except for the one shake-off, and Diaz ended the game by blowing a 99 mph fastball past former Met Jay Bruce to end a string of four straight losses to the Phillies in which the Mets held a lead in the sixth inning or later.

Before the game, manager Mickey Callaway said Diaz, who has already allowed more earned runs and home runs this year than he did in 39 more innings a year ago, was still his closer, in part because of what it could do to his psyche to demote him and the adverse effect it would have on the rest of the bullpen. Callaway then went back to Diaz, who got the job done for his 19th save in 23 chances.

“It just gave me the confidence that my team and my manager believe in me,” Diaz said. “To be able to have a good game like today, gives me the confidence I need going forward.”

Diaz retired Bryce Harper on a line drive right back at him, knocking it down with his glove and running it over to first base himself. He got Rhys Hoskins on a line-out to third, and after J.T. Realmuto singled and stole second base, Diaz struck out Bruce.

“That was big,” Callaway said. “You want something to happen good for this guy because he works so hard every day. He cares. He comes with energy every day. and his stuff is great.

“I’m proud of him for going out there tonight after a tough one [Friday] and going right through the heart of the order and making good pitches.”