NEW YORK -- When the bullpen door swung open after the sixth inning on Friday night, the familiar drumbeat of "Narco," Edwin Díaz’s popular entrance music, did not begin pulsing. But there was Díaz, jogging in as a promotion ran on Citi Field’s center-field scoreboard. Finally, as the right-hander reached the mound, the song started to play.

This is not what the Mets envisioned this offseason when they engineered a high-tech sound-and-light show entrance for Díaz. But it is the reality of their current situation. With Díaz still working out the kinks in lower-leverage spots, the club has been forced to look elsewhere at the ends of games.

That strategy directly harmed them Friday, when Reed Garrett gave up a go-ahead grand slam to Patrick Bailey in the eighth inning of an 8-7 loss to the Giants.

"I let it kind of snowball out of control," Garrett said. “I didn’t do my job and let the team down. … We played too good to let that happen."

For most of the evening, the Mets led thanks to home runs from J.D. Martinez, Mark Vientos and Pete Alonso. Given such a lead earlier this season, manager Carlos Mendoza might have turned to Garrett or one of his other setup men in relief of starter Christian Scott in the seventh. But Mendoza had been looking for a softer spot to reinsert Díaz, who hadn’t pitched since his four-run blowup in Miami last Saturday. A three-run margin seemed reasonable.

And indeed, Díaz appeared much improved, touching 99 mph during an outing that saw him strike out two of the four batters he faced. Díaz credited Francisco Lindor, who stood in the batter’s box earlier this week as the closer worked to perfect his glove-side fastball command. He believed that paid immediate dividends in the seventh inning Friday, which Díaz called his best outing of the season.

"I was able to do whatever I wanted on the mound," he said.

The problem was that after Díaz departed, the Mets still needed to cobble together six more outs. The obvious choice to pitch the eighth was Garrett, who initially seemed like his usual dominant self. Although Mike Yastrzemski opened the inning with a hit, it was a swinging bunt that struck the third-base bag. Marco Luciano followed with a bloop single into shallow right field before Garrett recovered to retire the next two hitters.

Moments later, everything flipped. Thairo Estrada hit an RBI double. Matt Chapman walked. And Bailey followed with a go-ahead grand slam as boos rained down at Citi.

"When it came to needing to make that big pitch," Garrett said, "I just didn’t execute."

Despite a spirited ninth-inning rally in which they scored a run and left the bases loaded, the Mets have now lost four consecutive games, including three in a row in which they’ve hit three home runs. (They’re the only Major League club to suffer that fate this season.) They’re a season-high 15 games out of first place. And they’re still not entirely sure how high-leverage situations might look for them going forward.

Asked if Díaz has done enough to regain his closer’s job, Mendoza didn’t directly answer, responding: "Yeah, look, we’re piecing it together right now. We’re mixing and matching. I liked what I saw today, especially the conviction. And that’s what it comes down to -- the confidence of Edwin. When he’s right, it’s pretty nasty."

What that means for Díaz in the short-term isn’t entirely clear, but it’s not as if the Mets are swimming in alternatives. Garrett, a darling of the early season, has lost two consecutive games and allowed at least one run in three of his past five outings. Another right-handed setup man, Adam Ottavino, has a 6.48 ERA in May, while the team’s top lefty, Jake Diekman, has walked eight of the past 30 batters he’s faced.

At this juncture, the team will be happy simply to have games to save. Despite the offense starting to click, the Mets have lost:

• Six of their last seven games
• Nine of their last 11
• Twenty-one of their last 30

The Mets are not only struggling but also are facing the prospect of a Trade Deadline selloff if they continue to lose. The bullpen, a strength on paper heading into the season, is one of many areas in which New York must improve.

"We’re angry," Mendoza said. "Obviously, we’re angry, and guys are going to be pissed. But at the same time, you have to stay positive. You’ve got to keep going."