Mets relief pitcher Craig Kimbrel reacts after giving up a...

Mets relief pitcher Craig Kimbrel reacts after giving up a grand slam to the Rockies' Jake McCarthy in the eighth inning on Thursday in Denver. Credit: AP/David Zalubowski

DENVER —  This is how the little things add up.

The Mets were tied with the Rockies in the eighth inning of their 6-2 loss at Coors Field on Thursday when Craig Kimbrel was conscripted into duty.

From the beginning, the veteran righthander didn’t quite look right. He allowed back-to-back singles to TJ Rumfield and Troy Johnston to lead off the inning and walked Willi Castro after a questionable non-call on a checked swing. That loaded the bases with none out for Jake McCarthy, who turned on a knee-high inside fastball and walloped it 448 feet to right, just inside the foul pole.

And just like that, the Mets, looking for their first sweep of the year, were felled by inefficiency and circumstance. But it’s not all on Kimbrel.

No, a lot of this was put into motion the previous day during a relatively breezy 10-5 win. It was then that Tobias Myers, staked to an eight-run lead in the sixth, fell apart, allowing four runs and forcing manager Carlos Mendoza to use Brooks Raley for 1 1⁄3 innings. By the time the ninth rolled around, the Mets had a comfortable six-run cushion, allowing Mendoza to turn to a generally ineffective Sean Manaea, who hadn’t pitched in seven days.

Manaea, whose lowered velocity is cause for grave concern, served up little more than batting practice. He allowed a run and three hits, plus a hit batsman, and recorded only one out.

That meant Devin Williams, who already had warmed up at least once, not only had to get back up in the bullpen but had to actually get into the game, nailing the final two batters via strikeout.

Luke Weaver was unavailable, having thrown 20 pitches the previous day, Mendoza said.

Asked how Wednesday’s win factored into Thursday’s loss, Mendoza allowed that it was “part of it, because we had to use a lot of our guys and obviously some of them weren’t available today.

“We got the win yesterday. I’m not going to blame that on them. We had chances today and we couldn’t add on there.”

While that’s true, it still has to sting. After a disastrous April, the Mets appear to be making headway on this very long western trip. They took two of three from the Angels but could have swept if not for a 10th-inning walk-off, and they were in prime position to sweep the Rockies, too.

Christian Scott, still limited in how deep he can pitch in his first season back from Tommy John surgery, gave his team a chance, allowing one run in 4 2⁄3 innings. But that short start also meant that a taxed bullpen would be taxed again, and the results speak for themselves.

Now, with their originally scheduled Thursday off day erased because of this week’s inclement weather, they travel to Phoenix with another prime opportunity ... but with a caveat.

They have Nolan McLean and Clay Holmes lined up for their first two games against the sub-.500 Diamondbacks, and the offense seems to be showing signs of life, Thursday’s weak performance notwithstanding (they went 1-for-9 with runners in scoring position). But at this point, little hiccups can have long-range ramifications.

You saw it with Myers, who otherwise has been excellent but has been relied on heavily  — 20 2⁄3 innings in 10 appearances.

Manaea is his own conundrum. Though he and the Mets insist he’s healthy, he still has loose bodies in his elbow and his fastball velocity has dipped 2 mph to an average of 89.7 — meaning he’s had to drop its usage in favor of his sweeper. He’s signed through next year, though, and the troubleshooting has turned into an all-hands-on-deck scenario.

“It’s a combination of a lot of things,” Mendoza said when asked what the team is doing to get the lefty right. “The pitching coaches are really digging in here, watching films and talking to Sean, getting some feedback from him. We need him. That’s the bottom line. This is a guy who is important for us and it’s our job as a coaching staff to get him back on track.”

There are other factors at play, too.

AJ Minter, who tentatively was slated for a May return, had his rehab shut down because of left hip discomfort, though the Mets don’t believe it to be a serious issue. No one knows if they’re ever going to get the version of Kodai Senga they saw in 2023. And David Peterson continues to be an enigma, though he’s looked better of late.

That leads to losses like Thursday’s.

Scott was called up to replace Senga and certainly looks as if he belongs, even as the Mets remain careful with his workload. But Freddy Peralta, a good but inefficient pitcher, also provided limited length Tuesday. Peterson, who worked as a bulk guy out of the bullpen Monday, also didn’t go long.

When you tack on what happened with Myers and Manaea, you get Kimbrel in a less-than-favorable situation.

“On the home run pitch, it was just location,” Kimbrel said. “I was trying to go up and I yanked it down. It really all started with the leadoff guy. I got ahead of him. I tried to bury a breaking ball, left it up, gave him an opportunity to put it in play and he got a hit.

“And then the [Rockies executed a] hit-and-run and then just really, right there, with first and third, I was trying to get a strikeout and I felt like I did. They didn’t feel like [Castro] went on the check swing and it turned into a walk, which turned into a grand slam.”

Which turned into a loss — a very apt reminder that all those little things do add up in the end.

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