In the second game of the Queens edition of the Subway Series, both the Mets and Yankees picked up momentum. It’s just that they’re going in different directions.

The Mets continued their ascent behind a pair of home runs by Pete Alonso that produced five runs and a first-inning grand slam by Brandon Nimmo that put them ahead for good in a 12-6 triumph Saturday before 41,401 at Citi Field.

The Yankees, on the other hand, just keep sliding. They also hit three home runs, but all were solo shots, and their losing streak grew to six games. They have been outscored 54-34 in that span.

The Mets (52-38) have won four straight games, the first time they’ve done that since a six-game winning streak capped by a June 12 victory over Washington.

There still are remnants of the brutal three-week stretch in which they lost 14 of 17 before this winning streak, but they seem to have turned the page on it with a better brand of baseball.

“It’s pretty simple to break it down — just the number of quality at-bats has gone up,” Nimmo said of the team’s turnaround. “When we out-quality-at-bat the other team, we usually win, and we’ve been able to do that lately . . . It’s the main name of the game.

“It’s usually a case of two or three more good at-bats [between] the teams,” he added. “But I feel like we’ve been really stacking them together well lately.”

The Yankees (48-41) have lost 16 of their last 22, and this is their second run of six straight losses in the skid. They fell three games behind the AL East-leading Blue Jays and have dropped seven of their past 11 series.

“It’s been a terrible week,” manager Aaron Boone said.

Nimmo’s grand slam was his second in the four-game winning streak and third of the season. One pitch after he flailed at a sharp-breaking low-and-away slider from Carlos Rodon to bring the count to 1-and-2, Rodon hung a fat slider and Nimmo hit it 387 feet to right-center to give the Mets a 4-0 lead.

“I feel like both of these teams right now are kind of like heavyweights at the end of a 15-round match — just trying to throw some haymakers — and both teams are pretty beat up right now,” Nimmo said. “So I do feel it’s a big deal when you’re able to get that lead there in the beginning.”

Alonso hit a 382-foot two-run blast to rightfield off Rodon in the fifth to give the Mets a 7-2 lead and a 392-foot three-run shot to leftfield off Jayvien Sandridge in the seventh to make it 11-5. He has 20 home runs and 73 RBIs.

Francisco Lindor chipped in with two hits, two walks, an RBI and four runs scored.

“We’re playing complete baseball on both sides of the ball and we’re finishing games,” Alonso said.

“I thought we did a great job of being aggressive in the zone when [Rodon] came in the zone, and when he wasn’t in there, we were pretty selective,” he added. “We were hunting our pitch today.”

“When we are controlling the strike zone as a team, we’re dangerous,” Mets manager Carlos Mendoza said. “[The] stretches where we will be quiet offensively, we don’t create much traffic, it’s because we’re going out of the strike zone and swinging at their pitches instead of forcing them to come in to our strength.

“The last few games, [Francisco] Lindor and [Alonso] are forcing pitchers to come into the strike zone,” he added. “They are special there. They are elite players.”

Ben Rice had an RBI double off Ryne Stanek in the eighth to make it 11-6. Lindor doubled into the rightfield corner and scored on Juan Soto’s rocket single off the rightfield wall in the bottom of the inning.

The Yankees had crept within 5-2 on solo home runs by Jazz Chisholm Jr. and Austin Wells before Alonso’s first home run. The Yankees pulled within 7-5 on Cody Bellinger’s two-run double in the sixth and Anthony Volpe’s homer in the seventh.

Rodon (9-6, 3.30 ERA) had shaken off some early-season struggles to become a bright spot and a strong performer, but on this day, he turned in arguably his worst performance of the season, allowing seven runs (six earned) in five innings.

The source of his early-season struggles was issuing walks in front of big hits, and they were the source of his problems on Saturday. He issued three walks and all three baserunners scored on home runs. The lefthander walked Lindor and Alonso in front of Nimmo’s first-inning grand slam. Lindor drew a four-pitch pass two batters in front of Alonso’s first home run.

“They’re a great team — they have great guys, but it’s not like they are un-pitchable,” Rodon said. “They put together good at-bats and today I had a lot of misses and fell behind on some guys. I should have been better at my craft, but today I wasn’t good enough.”

Mets starter Frankie Montas (1-1, 6.14) helped the Mets by pitching into the sixth. He exited one batter after Bellinger’s double cut the margin to three runs, allowed four runs and five hits without a walk and struck out two in 5 2⁄3 innings.