Mets third baseman Mark Vientos is batting .357 with two...

Mets third baseman Mark Vientos is batting .357 with two home runs in 31 plate appearances this season through games of May 22. Credit: AP/David Dermer

If the Mets are ready to decide, it really is no decision at all: Mark Vientos deserves to be the starting third baseman.

That is as much a reaction to Vientos’ very productive week as it is a result of Brett Baty’s continued inability to consistently hit — now across a full season’s worth of games. The Mets are at risk of their season slipping away, and here they have a straightforward, in-house, non-dramatic, reversible switch that legitimately could help.

Organizational decision-makers know all that, of course. If they weren’t open to the possibility of Vientos taking over, they would not have called him up last week. If they weren’t intrigued by his production against lefthanders, they would not have given him consecutive starts this week against righthanders.

Consider: Vientos has six extra-base hits in nine games this year. Baty has six in 43.

“He’s not missing pitches,” manager Carlos Mendoza said of Vientos. “He’s ready to go from pitch one and he’s getting pitches in the strike zone and he’s doing damage. It’s more of a shorter swing, he’s impacting the baseball, not chasing as much — not only against lefties but righties. I like where he’s at now.”

Conversely, Mendoza’s most recent insight on Baty: “He’s in between a little bit at the plate right now: not doing damage on the pitches that he needs to be doing damage [on], then chasing.”

This is relevant now, with the Mets set to open a homestand Friday against the Giants, because of comments from Mets bosses last week. When they brought up Vientos and sacrificed Joey Wendle — preferring to carry the extra bat over a backup middle infielder — they said they were comfortable with that arrangement for at least the duration of the road trip . . . which is over.

Hence, decision time: Roll with Vientos, stick with Baty or extend this two-man status quo — which can’t be a long-term fix.

Asked Wednesday afternoon whether the Mets had figured out what to do with the third basemen, Mendoza said, “We haven’t decided anything yet.”

That Vientos has done well in limited chances over the past month is a testament to his mental fortitude. His demotion to the minors at the end of spring training was a stunner. Whatever frustration — and anger and disappointment — existed then, though, seems not to have impacted his ability to do his job.

By all accounts, Vientos kept his head on straight when joining Triple-A Syracuse, worked hard, said all the right things and played well. The same was true during his three-day cameo in the majors last month — remember that walk-off home run? — and when he returned recently.

His numbers across those brief stints: .357 average (10-for-28) with a 1.133 OPS.

Compare that with Baty: .228 and .611.

Baty is regarded as a better defender — and, to his credit, he has remained stable in the field even as he has struggled at the plate — but the Mets need thump. With Pete Alonso staying hot, J.D. Martinez coming around, Jeff McNeil waking up and Vientos playing, you can squint and turn your head and see the kind of lineup the Mets thought they would have.

“Just trying to simplify things, not trying to do too much up there,” Vientos said. “Get my pitch and drive it. It all starts with the cage work and your routine and your plan.”

A demotion for Baty would be his second time losing the job, following a similar episode last August. It need not be a final verdict, though. He still is only 24. Plenty of players break out after a couple of false starts.

For the Mets, it would merely be an acknowledgment of the reality: Vientos is more likely to help them win games right now. That should be the priority.

Vientos said he learned how to handle a part-time role simply by being put in that position. The only way to find out about the full-time version is to do the same.

“Doing it before and knowing what it takes to be ready when your name is called. So, experience,” he said. “It’s been, what, two years now?”

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