The Mets haven’t won back-to-back games since June 1. Perhaps a visit from the Keystone Cardinals will get them going.

What figured to be a midseason matchup between two of the top teams in the National League has turned into something else.

As much of a mess as things are in Queens, with the Mets four games under .500, 10 games behind the first-place Braves in the NL East and four games out of a wild-card spot despite a record-high payroll, the situation in St. Louis may be even worse.

No, the Cardinals didn’t spend a ton of money last offseason, but they did sign an expensive replacement for retired catcher Yadier Molina and entered the season with plenty of observers picking them to win the NL Central.

But heading into the start Friday of a series between the two disappointing clubs at Citi Field, the Cardinals find themselves in last place in their division.

St. Louis is eight games behind surprising first-place Pittsburgh and in even worse shape in the NL wild-card standings, 9 ½ games out of the last playoff spot.

The Cardinals have lost five straight and 10 of 12 to fall to 27-42. This from an organization that’s made the playoffs the previous four seasons and nine of the last 12, starting in 2011, when it won the World Series.

The signing of Willson Contreras to succeed Molina has been a disaster.

The organization changed course and announced Contreras would be switched to an outfielder/DH role barely a month into a five-year, $87.5 million deal, only to reverse the decision a week later.

Nothing has worked for the 30-year-old, who currently is on pace for his worst offensive season of his career.

And outside of former Yankee Jordan Montgomery, the pitching staff has been mostly terrible.

Third baseman Nolan Arenado expressed his frustration following the Cardinals’ most recent loss, to the Giants on Wednesday.

“We’re not getting outs when we need to [and] putting guys away,’’ Arenado said, according to the St. Louis Post-Dispatch. “We’re not playing defense. We don’t execute. That’s why we’re playing the way we’re playing.”

According to Playoffstatus.com, the Cardinals have just a 3 percent chance of making the playoffs. Only the historically bad Athletics and Royals have worse odds.

Compared to that, the Mets don’t look so bad. They did, though, fall to a season-worst five games under .500 with their loss to the Yankees on Tuesday at Citi Field before they rebounded with a win on Wednesday.

Neither team, though, was expected to be at or near the bottom of the standings this far into the season.