The Mets lost one more piece in the name of development, but this one represents a different case.

Brett Baty was optioned Monday, when the club officially decided the third baseman would be better off learning and adjusting with Triple-A Syracuse than continuing to struggle in the majors.

The Mets’ trade-deadline sell-off sent the message that the rest of this season would be more about improvements than results. Even if the Mets did not have an obvious, immediate upgrade at third base, the development of Baty outweighed the roster needs.

“Just a little timeout. Kind of: Take a breath,” manager Buck Showalter said after delivering the news to Baty with general manager Billy Eppler. “Just let him kind of work on some things without the day-to-day [scrutiny].

“I think it’s in his best interest to go down, take a breath and get back to what he was doing when he first got here. [The majors is a] tough place to do that.”

The promising 23-year-old tore up the minors in April, which prompted a call-up to a win-now club. But Baty’s play has declined since and dramatically recently.

Baty went 0-for-18 with eight strikeouts during the six-game road trip through Kansas City and Baltimore, his OPS dropping to .620 in 86 games this season.

He had blasted five home runs in 42 plate appearances with Syracuse to begin his season. Upon being called up, he hit just seven homers in 311 plate appearances, lacking both in power and contact.

As a rising prospect, his bat was better regarded than his glove. He has struggled defensively and was rated, by Statcast’s Outs Above Average, as 36th among 40 qualified third basemen.

Before his club opened a series at Citi Field against the Cubs, Showalter suggested the demotion was about more than numbers.

“The day-to-day scrutiny and not necessarily the pressure, but … everything you do here can snowball,” Showalter said about Baty, who can work in Syracuse and make an occasional error without a dropped pop-up going viral, which one did last month.

If Baty were hitting, though, the occasional fielding flub could be forgiven. He came up through the system with impressive exit-velocity numbers but a reputation for hitting the ball on the ground too much. He focused during his breakout 2022 campaign on lifting pitches more often.

The problem reappeared at the major league level. Among hitters with at least 300 plate appearances, Baty’s 51.3 percent groundball rate entered play Monday as the 15th highest in baseball.

Swing changes are much easier to make away from the spotlight and against minor league pitching.

“Just because something’s delayed doesn’t mean it’s denied,” said Showalter, who expressed hope that Baty would take a short break before playing his way back to the majors. “Hopefully it’s a temporary thing, but I told him he controls it. It’s up to him. He’s got a good attitude about it.”

Optioning Baty opened the door for another struggling, developing prospect to receive more chances at third base. Mark Vientos has clobbered Triple-A pitching (1.000 OPS) but has not brought the big bat to Queens, and the same defensive issues have haunted him at the major league level.

The 23-year-old mishandled another grounder Sunday in Baltimore and is trying to prove he can be more than a designated hitter.

In the Mets’ first game without Baty, Danny Mendick got the start at third, but Showalter indicated Vientos likely would get a prolonged tryout to play third base.

“I don’t want to completely commit to it, but that was kind of my thought initially when Billy and I were talking about this,” Showalter said.