Todd Frazier walks off the field after being erased on...

Todd Frazier walks off the field after being erased on a double play in the ninth to end the Mets' 4-3 loss to the St. Louis Cardinals on Sunday, June 16, 2019, at Citi Field. "We know we're better than this," Frazier said later of the club losing three out of four to St. Louis and falling to three games below .500. Credit: Kathleen Malone-Van Dyke

The Mets can tell us over and over how agonizingly close they are to winning these games, to stringing a few victories together, to reaching .500 and then “really taking off,” as Mickey Callaway likes to put it.

But does anyone actually believe that?

Even inside their own clubhouse, the players have to be rolling their eyes at Callaway’s pep talks after dropping three of four to the so-so Cardinals this weekend, including Sunday’s been-there, done-that 4-3 loss at Citi Field.

Shuffle the names, the result still ends up the same. This time it was Chris Flexen — part of Brodie Van Wagenen’s bullpen shakeup — who hung a slider to Paul DeJong for the tiebreaking homer in the eighth inning. DeJong, with four dingers in his last five Citi games, is turning into a regular Chipper Jr. But if it hadn’t been him, it would have been someone else. Take your pick.

“We both were one swing away,” Callaway said. “They got the big one.”

Why do the Mets never get the big one? Because teams that are forever chasing .500 don’t get the big one on a consistent basis. They lose their starting pitchers to freak injuries in the middle of games, first Noah Syndergaard (hamstring strain) on Saturday, then Jason Vargas on Sunday. His left calf suddenly cramped up during his fourth-inning at-bat.

“I’ve never experienced that before,” he said, “especially on a swing.”

Of course not. Because it had to happen, for the first time, on a day when the Mets’ bullpen was virtually spent.

Still, Callaway got three scoreless innings from Wilmer Font and another from the newly acquired Brooks Pounders. In between, however, Flexen made the pivotal mistake — a poorly executed pitch at the wrong moment.

“That’s exactly what it was,” Flexen said.

Isn’t it always? Jeurys Familia, Edwin Diaz. One bad pitch. Or three. Or 10. Regardless of whatever good the Mets are able to do through the first six or so innings, it inevitably is erased in painful fashion.

On Sunday, Callaway rested Jeff McNeil, Todd Frazier and Amed Rosario, yet the Mets were able to rally from a 2-0 deficit to take a 3-2 lead in the third inning, thanks to RBI singles by Adeiny Hechavarria and Juan Lagares.

As usual, it didn’t stick. The Cardinals tied the score in the fourth on Yadier Molina’s double-play grounder, but only after the Mets failed to turn two earlier that inning when Hechavarria couldn’t hold on to a throw from Vargas for the team’s 53rd error, most in the National League.

The Mets lost this game despite outhitting the Cards 10-3. On Saturday night, their one victory, the Mets had to hold on for dear life, and only McNeil’s game-ending dime of a throw home saved Diaz from another blown save.

Every day is a struggle. There’s a reason the Mets are three games under .500 (34-37) and 7 1⁄2 games behind the division-leading Braves. It’s not bad luck.

“We know we’re better than this,” Todd Frazier said. “If you’re around .500, you have an opportunity — at least for a wild card.”

With all due respect to Frazier, the Mets are right where they should be, and they need to stop talking about .500 as if it means anything more than finally achieving the very definition of mediocrity.

This isn’t the NBA. Not everyone makes the playoffs, or even contends for a spot. You need to be among the best teams in your league. The Mets aren’t that. And without Syndergaard for a while, they’re going to be even worse.

“We’re putting ourselves in position to win games,” Callaway said.

Actually, just close enough to lose them. But if the Mets want a refresher course on what first-place teams look like, they’ll get two of them on this upcoming road trip, which includes stops in Atlanta (three games), Wrigley Field (four) and Philadelphia (four).

It’s not hyperbole to suggest that this stretch could define their season, a last stand of sorts. By the time the Mets return to Citi Field to host the Yankees in early July, we could be looking ahead to the trade deadline, with the Mets planting a “For Sale’’ sign off Roosevelt Avenue.

“We’ve got to find ways to win,” Frazier said.

It’s the battle cry for every team trying to keep their heads above water, as if all of a sudden they’ll figure it out. As if they can make it happen if they say it often enough. But it’s always going to be that one swing, or one pitch, that defines them.

And as we saw again in Sunday’s loss, the Mets keep ending up on the wrong side of those moments. It’s not a coincidence.

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