If the Mets are looking to shop Jason Vargas, now might be the best time.

Through six innings against the Padres on Tuesday, Vargas allowed just one hit and recorded eight strikeouts, three of which came against Fernando Tatis Jr., Pete Alonso’s closest competitor for NL Rookie of the Year honors. Vargas threw 99 pitches — 57 for strikes — as the Mets took full advantage of the lefty’s lights-out performance on the way to their 5-2 series-opening victory.

“Just a wicked changeup, and they can’t lay off it,” Mets manager Mickey Callaway said. “That thing must look thigh-high coming through the zone and next thing you know it’s down at their shoestrings. He just continues to execute pitches.

“I love when a guy is throwing 83 mph and he’ll pound you and back you off the dish, that’s one of the coolest things ever. You try to get guys that throws 95 mph to do that and they won’t.”

Vargas, who might be on the move as the July 31 trade deadline approaches, said he knew from the start his changeup had depth Tuesday. From there, he focused on maintaining it low in the zone, hoping for swings and misses. After hearing Callaway’s appreciation for his throwing speed, Vargas noted how just throwing hard is losing its novelty.

“I guess I’m on the other end of the spectrum now,” he said. “I just try and do my best to keep it out of the fat part of the plate, where everybody is looking to do [damage]. I just think that I’m the only one who throws that slow.”

The win brought Vargas’ record to 5-5, with a 3.96 ERA.

In his three previous outings, Vargas allowed a combined 17 hits and 12 earned runs, along with five homers. His eight strikeouts Tuesday were among his top-three totals of the season, with the lefty striking out 10 against the Phillies on June 26 and another eight on June 5 against the Giants.

“He just knows how to pitch. He’s not afraid, he’s going to execute pitches, and he’s never going to give in,” Callaway said. “Lately, for a long period of time, most of the year this year, he’s done a heck of a job. And been the Jason Vargas that we knew he could be.”