The Mets are doing their best to make sure the Nationals play as many meaningless games the rest of the year as they will. So far this weekend, they’re happily supplying the hammer and nails for their rivals’ coffin.

The two-time defending NL East champions reached Queens on Friday on the outskirts of the playoff race, six games behind in the loss column of the second NL wild-card spot. But after getting shutout for a franchise-record third straight game, they have the same postseason pulse as the Mets: nonexistent.

Zack Wheeler became the latest pitcher to tame this once-dangerous lineup, and Amed Rosario and Todd Frazier each went deep on 0-2 pitches as the Mets blanked the Nationals, 3-0, at Citi Field in front of 29,868 to win for the eighth time in 12 games.

“We know it’s the Nationals. We know we have had our struggles against them. You can feel it,” manager Mickey Callaway said. “It should be there. That’s what keeps you going, and it makes those games really, really fun. You come out every day and you want to kick somebody’s butt.”

Wheeler, one of the few bright spots in this ugly Mets (58-71) season, won a personal-best seventh straight decision. Scattering six singles and striking out four, he threw seven shutout innings, lowered his ERA to 3.46. He held the Nationals (64-66) to just one hit in eight at-bats with runners in scoring position.

“I hope this is who he is. I think he can be this,” Callaway said. “But from a feeling that the team has when he’s starting that day, absolutely we feel like [Jacob] deGrom’s on the mound or [Noah] Syndergaard’s on the mound. He’s in that category now.”

Rosario produced the game’s first run in the home sixth, blasting a grooved 0-2 Tanner Roark fastball over the fence in left-center field for his seventh homer of the year. It was his sixth multi-hit game of the month and the 19th game in his past 30 contests in which he has hit safely since moving predominantly to the leadoff spot. Frazier added his 15th homer in the seventh and Michael Conforto plated another run with a single in the eighth.

Wheeler wasn’t dominant — he walked three for the first time since July 9, eight starts ago — but he continued to show his evolution as a pitcher by grinding through his inefficiency. With runners in scoring position in the first, third, fifth and seventh, Wheeler never gave in and made quality pitches to escape jams.

“I didn’t have my best stuff. Maybe in years past, it wouldn’t have gone so well,” he said. “But I feel so good mechanically and in sync, being able to repeat that type of stuff, I can lock back in and go right after them.”

That doesn’t mean he’s satisfied, however.

“I think there’s another step ahead,” Wheeler said, “where you can actually go out there and just dominate rather than go out there and do well.”