Mets’ recent stretch has made one thing clear

The Mets, who began the season frigid (with five straight losses), rebounded quickly (winning 12 of 15) and have essentially traded cold streaks and hot streaks the rest of the way, have finally found a middle ground.

Since getting swept in Seattle three weekends ago , Carlos Mendoza’s group has not won three straight or lost three straight.

Against teams they might have stomped (the A’s and Marlins), they instead came away 3-3.

Against teams they might have slipped against (the Orioles and Padres), they held serve in going 4-3 .

What has become clear is that the old Wilpon goal — to play meaningful games in September — will be accomplished.

What also has become clear is that continued mediocrity probably wouldn’t be good enough.

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The Braves, despite their spate of significant injuries, entered play Monday having won six of eight and own the easier remaining schedule.

Atlanta, which was 2 ½ games ahead of the Mets for the final NL wild card, entered action Monday with the ninth-easiest schedule the rest of the season, according to FanGraphs, which helped the site estimate the club had a 79.9 percent chance of reaching the postseason.

The Mets, who begin another enormous, three-game series on Tuesday in Arizona, held the 17th-easiest schedule and a 20 percent chance of playing in October.

That means stacking up respectable but not excellent series, like the one they just split in San Diego, likely wouldn’t equate to a postseason entry.

“Today was a tough one. Needed that one,” J.D. Martinez said after the Mets bullpen blew a two-run lead in the final two innings of a walk-off loss to the Padres on Sunday. “Especially given the circumstances of where the standings are and everything.

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“But still a lot of baseball left.”

About five weeks and 31 games left of baseball for a team that does have enough time to make up ground but would have to reach another gear, particularly against top-tier competition.

Up first is a series against the Diamondbacks, who hold the first wild-card spot and have won six in a row and 26 of 34 in the second half.

No one in baseball has scored more than the high-powered Diamondbacks, who are averaging 5.35 runs per game (although their best hitter, Ketel Marte, is sidelined with a sprained ankle).

It will be Sean Manaea, Luis Severino and either David Peterson or Tylor Megill, who will replace the injured Paul Blackburn, tasked with quieting that offense.

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And the Mets bullpen, which watched the normally reliable Jose Butto and Edwin Diaz falter Sunday, to close games out.

“You just got to turn the page and be ready for a really good series again,” Mendoza said after the Mets couldn’t escape San Diego with a series victory. “Another good team that we got here in the Diamondbacks.”

Martinez said he does not pay a ton of attention to the standings, but, “I just know that we have these two guys in front of us, these two teams we’re facing,” he said of the Padres and Diamondbacks. “These are [games] that we have to win.”

After this series, the Mets will have just three games left against a fellow NL wild-card contender: Sept. 24-26 in Atlanta, the site where their long-held NL East lead fell two years ago.

For the penultimate series of their season to matter, the Mets would have to find another hot streak in a season that has had several.

More encouraging at-bats from the likes of Brandon Nimmo and Francisco Alvarez would help.

But continuing this prolonged stretch of merely playing OK — going 19-17 since the All-Star break — likely would mean another season that ends in disappointment.

“We still got a month left,” Martinez said. “A lot of crazy stuff happens in September.”

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