NEW YORK -- A Mets team that has spoken for months about the value of accountability put that concept into practice once again on Monday, designating struggling reliever Jake Diekman for assignment. Diekman had produced a 5.63 ERA in 43 appearances with the club.

The Mets called up left-hander Matt Gage from Triple-A Syracuse to replace him.

One of the team’s primary offseason bullpen signings, Diekman never found consistency with the Mets and struggled in July in particular. Although Diekman’s month did include a signature moment, when he froze Aaron Judge for a crucial ninth-inning out in the Mets' win over the Yankees last Tuesday, Diekman allowed eight runs over 6 2/3 innings in July.

“Not an easy one, especially because you’re dealing with a guy like Diek who’s been here since Day 1 of Spring Training,” manager Carlos Mendoza said. “He was such a professional. He was always willing to take the baseball, and when it was hard for him going through his struggles and things like that, he was always available. He always wanted to be there. But we got to a point where we needed to make a decision.”

Because Diekman was making $4 million and any team that claims him off waivers would absorb the remainder of that salary, he stands a decent chance of clearing waivers. Diekman does have the right to reject an outright assignment to the Minors, however, at which point the Mets would be forced to release him and pay the remainder of his salary (minus a pro-rated portion of the Major League minimum if Diekman subsequently signed elsewhere).

Of note, Diekman’s contract included a $4 million team option that would have become guaranteed if he appeared in 58 games. The Mets will no longer be on the hook for that.

The Mets are now without both veteran left-handers from their Opening Day bullpen: Diekman and Brooks Raley, who recently underwent Tommy John surgery and is out for the season. The team has backfilled with Danny Young and Alex Young, each of whom have enjoyed success in the big leagues, and now Gage as well.

“You’re always looking for the next guy and hoping to get better,” Mendoza said. “But it’s been a bit of a challenge, to be honest with you.”

Gage, 31, came to the Mets in a cash deal from the Dodgers earlier this month. He has since thrown 5 1/3 scoreless innings for Triple-A Syracuse. Over 16 career big league appearances, Gage has held lefties to a .425 OPS.

The Mets could look to acquire additional left-handed relief help before Tuesday’s 6 p.m. ET Trade Deadline, with Scott Alexander, Jalen Beeks, Andrew Chafin and Tanner Scott among a long list of potentially available arms.