Clay Holmes entered this weekend’s series in Phoenix with the second-best ERA (1.69) in the National League.

The right-hander ranked within the top 10 in WHIP (0.98), opponent batting average (.184) and innings pitched (42.2) as well.

But another stat is perhaps even more telling of Holmes’ early-season excellence.

Going into Friday night’s series opener against the Arizona Diamondbacks, the Mets were 5-2 in games started by Holmes — a .714 winning percentage — compared to 9-21 (.300) when anyone else started.

Indeed, the 33-year-old Holmes has elevated his performance in his second season as a full-time starter.

“He’s just on another level right now, physically, mentally,” manager Carlos Mendoza said recently. “The way he’s making adjustments in games. The way he’s using his pitches, trusting the defense when he needs to.”

A two-time All-Star as the crosstown Yankees’ closer, Holmes signed a three-year, $38 million contract with the Mets before the 2025 season with the mission of converting to the rotation.

Last season was a success for Holmes, who went 12-8 with a 3.53 ERA in 165.2 innings over 33 appearances (31 starts).

But Holmes (4-2) credits this year’s increased emphasis on his sinker — his bread-and-butter pitch as a reliever — for his dominant beginning to 2026.

Going into his start against the D-Backs on Saturday night, Holmes was throwing his sinker 49.7% of the time, up significantly from 40.8% last year.

His groundball rate of 57.4% was thus up a few ticks this season, ranking within MLB’s 93rd percentile.

“Especially now, I just feel like there’s a lot of confidence and trust with the sinker,” Holmes said recently. “That’s who I was as a reliever, and I knew that was who I would be as a starter, but I just had the confidence and trust with the sinker, and when I have that, I feel like I’m able to pitch off of it.”

Holmes isn’t relying as heavily on his sinker as he did as a reliever. He threw that pitch 69.3% of the time in 2023 and 56.2% in 2024.

The hulking right-hander regularly throws four other pitches, including a sweeper and a curveball that have been effective putaway weapons this year.

But it all starts with his sinker — a belief Holmes fortified throughout his transition to the rotation.

“I knew I would have to expand the arsenal. It wouldn’t be all sinkers,” Holmes said.

“With that, I’m not gonna say ‘distracted,’ but you know there has to be some widening of the arsenal, and so there was focus there. I think more than anything this year, the confidence in the sinker [is], like, I can still pitch off of this. It’s more of a mentality thing, just attacking with the sinker.”

Run support has been at a premium on a Mets team that’s struggled to score runs.

The Mets went into Friday with a 1-6 record in games started by Nolan McLean, despite his sterling 2.97 ERA. They are 3-5 in games started by Freddy Peralta, who boasts a similarly strong 3.12 ERA.

That’s why Holmes’ steady stinginess looms so large.

Entering Saturday, Holmes had pitched at least five innings in all seven of his starts and gotten through six innings in four of them. He did not allow more than two runs in any of those outings.

“When you’ve got a guy that, every time he takes the ball, he’s giving us a chance, that’s contagious,” Mendoza said.

“I’m pretty sure Freddy, I’m pretty sure [Christian Scott], Nolan, [David] Peterson, those guys understand the importance of pitching deep in games and giving the team a chance to win a baseball game. Like I said, that can be contagious.”