FOR NOW & TOMORROW

With lineup on borrowed time, Mets need kids to show promise

JUPITER, Fla. — Sandy Alderson coined a motto and a motivation for his 2017 Mets when he declared them “all in.”

This is the proper sentiment when your team possesses arguably the majors’ best rotation. But that rotation is not going anywhere. The Mets control through next season all seven starters who so excite them — Jacob deGrom, Robert Gsellman, Matt Harvey, Seth Lugo, Steven Matz, Noah Syndergaard and Zack Wheeler.

As for the rest of the roster, well, the right term might be “all out.”

Fi t t i n g l y, Alderson and Te rr y Co l - lins are in the f inal season of their contracts as they preside over an All Walk Year squad, particularly when it comes to the positional group. Jay Bruce, Lucas Duda, Curtis Granderson, Jose Reyes, Rene Rivera and Neil Walker all will be free agents after this season.

Asdrubal Cabrera has an $8.5 million option (or $2 million buyout) for next season and as David Wright exhibited again this week, the Mets can’t count on him for 2017, much less 2018.

So aside from Yoenis Cespedes in left, the Mets are not set anywhere moving forward because they also are uncertain behind the plate with Travis d’Arnaud and Kevin Plawecki. In addition, main set-up men Addison Reed and Fernando Salas will be free agents, while Jerry Blevins has a 2018 option.

Perhaps the only other team facing as much defection beat the Mets in the 2015 World Series. Lorenzo Cain, Alcides Escobar, Eric Hosmer and Mike Moustakas are Royals in their walk years. And in the offseason, Kansas City traded free-agents-to-be Wade Davis and Jarrod Dyson, and extended Danny Duffy’s contract. Conversely, the Mets essentially doubled-down on last year’s roster, which creates potential logjams in 2017 — particularly in the corner outfield — but lack of clarity thereafter.

“We definitely talk about it,” assistant GM John Ricco said. “It came up in the context of the Walker negotiations [as a way to solve a problem]. Part of this season is about evaluating what we have.”

The assessments are ongoing. On Wednesday against the Cardinals, the bookends to the Mets’ lineup were Granderson leading off and Rivera batting ninth. In between were options for depth this year and /or roles next year: Juan Lagares, Michael Conforto, Wilmer Flores, Brandon Nimmo, Gavin Cecchini, Amed Rosario and T.J. Rivera.

Ricco said picking up Cabrera’s option addresses some issues because he can serve as insurance if Rosario is not ready to play shortstop at the outset of next year or play second or third if Rosario is ready. Ricco also said the relationship is such with Reyes that if “it fits, he would probably want to come back, and we would feel pretty confident about a meeting of the minds.”

Ricco added, “I don’t think we will have to sign five free agents. Some of the answers will come from within and I think between now and July we will get a better idea of what we have and what we need.”

Ideally, Conforto’s early spring symbolizes he is back as an offensive asset. But Conforto, 24, is going to need to keep hitting as he faces crisper off-speed stuff. At Triple-A, the leaner, defensively adept Dominic Smith must show he can stay in shape and continue to add power while Rosario simply has to demonstrate he does not need more time to incubate his enticing tool set.

Rosario and Smith, both 21, are clearly the Mets’ best positional prospects. The distant next two are probably Nimmo and Cecchini, Alderson’s first two top picks in 2011-12. I spoke to a personnel chief and two scouts who cover the Mets systems and none saw that duo as anything better than reserves.

But the Mets still dream. They believe Nimmo, who turns 24 this month, has aboveaverage on-base skills and continues to get stronger, promising future power. Scouts like the 23-year-old Cecchini’s batto-ball skills, but not his power and certainly not a scattershot arm from short and third. But Collins praised how well Cecchini has taken to second base, notably with the precision of his throws.

Since the Mets would probably never deal Rosario — a top-10 prospect in the game — and would be loath to move Conforto or Smith, they need Nimmo and Cecchini to thrive at Triple-A or as major league reserves to make them more attractive July trade options.

“If I were a betting man, I would bet that Nimmo is on another team at the deadline,” one of the scouts said.

Both the Mets and scouts wonder if T.J. Rivera, 28, can ever have enough plate discipline to succeed in the majors and whether Plawecki, 26, will ever hit enough to even be a backup.

The volume of potential free agents suggests the Mets will have money to spend next offseason. But that starry rotation is getting more and more expensive. And mass additions of free agents has often proven to be bad business due to cost and the difficulty on hitting on so many external, less-wellknown alternatives.

Which is why even in an “all in” year, t he Mets turn i n wa r d f irst to see about answers for 2018. joel.sherman@ nypost.com