NEW YORK -- Two cogs of the back end of the Mets' bullpen, Seth Lugo and Dellin Betances, are in the rotation and on the injured list, respectively. Given that situation, the Mets entered Sunday badly needing strong performances from everyone else in that group -- particularly Edwin Díaz, who had shown signs of a renaissance in recent weeks.

Instead, Díaz blew his third save of the season, sending the Mets to an 8-7 loss to the Yankees in the first game of a doubleheader that they entered the seventh inning leading by five runs.

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An Andrés Giménez fielding error, a walk and a Luke Voit two-run single through the shift brought the tying run to the plate in the seventh, and that prompted Mets manager Luis Rojas to turn to Díaz. He subsequently allowed a game-tying two-run homer to Aaron Hicks, and then served up a walk-off single to Gio Urshela in the eighth.

Since joining the Mets last season, Díaz is 28-for-38 with a 5.80 ERA in save opportunities.

"We still trust him," Mets manager Luis Rojas said. "We still love his stuff. And that's when he's going to get the ball, when there's tight situations, when there's tense situations like that."

It is in those situations, however, that Díaz has routinely disappointed the Mets since they acquired him and Robinson Canó in a blockbuster trade two years ago. Sunday, according to Rojas, Díaz had little feel for his slider, despite the fact that he threw eight of nine breaking balls for strikes. That forced Díaz to "rely on one pitch," the fastball, which Hicks lined over the wall in right field for a homer.

The rallies undid the early work of the Mets' offense, which relied on a Canó two-run homer and a Michael Conforto two-run double to build a five-run lead.

"He only threw a few good sliders," Rojas said of Diaz. "That was kind of the story of his outing today. When he has those two pitches working for him, that's when it's really tough to get a barrel on him."

What has frustrated the Mets about Díaz, particularly this season, is that he often seems not just dominant but unhittable. From Aug. 2-19, Díaz struck out 19 of the 34 batters he faced. He entered Sunday's play with a rate of 21.0 strikeouts per nine innings, easily tops in the Majors among those with at least 10 innings pitched. That's why Rojas was comfortable turning to Díaz instead of other options in his depleted bullpen.

But when opposing batters hit Díaz, they hit him hard. Last year, Díaz served up 15 homers -- as many as in his previous two seasons combined. This year, four of the 12 hits against him have gone for extra bases, including the letter-high fastball that Hicks hit for a homer.

An inning later, the Yankees began with an automatic runner on second base because in a seven-inning doubleheader game, the eighth represented the first extra inning. Díaz induced two flyouts, before giving up Urshela's walk-off single.

"It's a tough one, that's for sure," said Mets starter Rick Porcello, who allowed two runs in five innings. "You never like to lose. Especially when you're winning a ballgame and end up giving it up late, it hurts. But this is something that you play baseball long enough, you deal with on more than one occasion and you know how to respond."