A pair of slumping Mets at the bottom of the order delivered the biggest swings on Thursday to send them out on top.

No. 8 hitter J.D. Davis crushed a grand slam and No. 9 hitter James McCann added a three-run shot to lead the way in the Mets’ 10-0 win over the Marlins at Citi Field.

Trevor Williams also put together his best start of the year, throwing seven shutout innings of two-hit ball and striking out seven as the Mets (52-31) enjoyed an all-around beatdown of the surging Marlins (39-42).

“We have the utmost confidence in ourselves and the guys in the dugout,” McCann said. “Something so special about this team is it’s not just one guy or two guys in the lineup that are getting the job done. If you look across the season, it’s been a different guy really every day. … So seeing the lineup produce the way it did tonight, that’s a lot of fun.”

Davis went 3-for-4 with a career-high five RBIs, falling a triple short of the cycle. He had entered Thursday hitting just 6-for-36 with one extra-base hit and one RBI over his past 13 games while losing some playing time to the red-hot Dominic Smith.

But the designated hitter blew the game open in the fifth inning with his first career grand slam, putting the Mets up 10-0.

“I think anybody in my shoes, if you get so many line-drive outs, it could be frustrating when you’re trying to change something or in that case trying to do too much,” said Davis, who owns MLB’s top hard-hit percentage without the results to show for it. “I think that’s where I got a little ahead of myself over the last week and a half, just trying to do too much instead of being balanced at the plate and staying through the baseball.”

Davis added a rally-starting double in the third inning and an RBI single in the fourth.

McCann, who came through with a key RBI single in the 10th inning of Wednesday’s 8-3 win over the Reds, still entered Thursday just 3-for-21 in seven games since returning from hamate surgery. But the catcher unloaded on a cutter down the middle from Marlins left-hander Daniel Castano in the fourth inning, blasting a three-run home run that put the Mets up 6-0.

The home run was McCann’s second of the season and first since April 22, with the drought in between also including six-plus weeks on the injured list.

“It hasn’t been going great since coming back, but I definitely feel like the strength is starting to come back,” McCann said. “I’m starting to get my timing, my feel, everything and string some quality at-bats together.”

Williams, meanwhile, retired the first seven batters he faced before Miguel Rojas doubled with one out in the third inning. But the right-hander quickly returned to dominance from there, retiring the next 13 batters he faced before allowing a two-out single in the seventh inning.

While Williams could be headed back to the bullpen after this start — the latest move in his season of bouncing between roles — he has given the Mets important innings.

“I’m proud to be a New York Met in any capacity,” Williams said after lowering his ERA to 3.76.

Brandon Nimmo, who chipped in an RBI double, also added some defensive flair to the night in the fifth inning. He ran full-speed to deep center field, then leapt onto the warning track to snag the fly ball and rob Jesus Sanchez of extra bases.

“The catch that Nimmo made in center field,” manager Buck Showalter said, “that’s as good of a catch as anybody you want to see.”