Jason Vargas, the Mets' newest starting pitcher, at his introductory...

Jason Vargas, the Mets' newest starting pitcher, at his introductory news conference. Credit: Newsday / Alejandra Villa

PORT ST. LUCIE, Fla. — The Mets had to remind themselves how quickly things can change.

Noah Syndergaard and Matt Harvey can talk about how healthy they feel. Zack Wheeler can say he’s fired up and wants to prove himself. But none of that erases the fact that health and prosperity are never guaranteed. It was the mistake the Mets made last year, and the mistake that Sandy Alderson was in no hurry to repeat.

So say hello to Jason Vargas. And while you’re at it, say goodbye to the possibility of the Mets making any more big moves this offseason.

The Mets on Sunday officially announced the signing of the 35-year-old lefthander — a two-year, $16-million deal with a club option for 2020 and incentives — and Alderson confirmed that this likely will mark the end of the Mets’ big moves.

It appears the Mets will have only one lefty in their bullpen — Jerry Blevins — but they’re not currently on the hunt for more.

“I was telling somebody the day after we signed Jason that it felt like the day after finals, when the semester was over,” Alderson said. “We’ve come a long way from the trade deadline last year . . . With Jason signing, we’re pretty much where we want to be.

“Now everybody including Jason goes out and performs, in terms of where we were and where we are right now, I think we feel pretty good. It doesn’t mean you are not always looking for ways to improve the team, but I would be surprised if not shocked if somebody walks into this clubhouse.”

Vargas, a former Royal, made the All-Star team for the first time in his 12-year career last season before hitting a wall in the second half. He had a 2.62 ERA before the All-Star break and a 6.28 ERA after that, finishing at 18-11 with a 4.16 ERA.

Vargas had a resurgent September last year, and he said then-Royals pitching coach Dave Eiland — who campaigned to sign him after taking the same position with the Mets — was instrumental in fixing the problems that plagued him.

“We just went back to working on some of the basic simple things mechanically and then really just trying to focus on pounding the bottom of the strike zone and, most importantly, that down-and-away fastball to a righthander,” Vargas said. “Once we got our thumb on it and figured out what the cause was and started making the right pitches, we both had a good idea that was the issue that was going on.”

Alderson said the signing isn’t any indication that the previous five starters — Jacob deGrom, Syndergaard, Harvey, Steven Matz and Wheeler — are injury-prone, only that the Mets have a decent memory.

“When this came together, it was probably at a moment of highest optimism because we were in camp and our guys all looked good, throwing early, and you have to remind yourself that there’s this ebb and flow over the course of a season that is health-related and performance-[related],” Alderson said, adding that the Wilpons were heavily involved in the move. “Of those pitchers that were available of his quality, he was our No. 1 choice.”

Vargas’ addition does mean that one of the original starting five likely will move to the bullpen — possibly Wheeler, who hasn’t pitched in a full season since 2014. There’s also the possibility of any of the backup starters — such as Seth Lugo or Chris Flexen — starting the year in Triple-A.

“We have to think about who needs to stay stretched out, who can bounce back, who has the pitches that can perform out of the bullpen versus starting,” manager Mickey Callaway said of that decision. “There’s a ton of factors that are going to be taken into account, and just because one of these starters doesn’t end up being in the bullpen and ends up in Triple-A doesn’t mean — it’s not that big of a deal about how we feel about them. We’re just trying to put ourselves in the best position to win every game. I think they’ll understand that in the end because that’s a tough thing to handle.”

Reyes happy to be back. Jose Reyes said Sunday it was never a question where he hoped to end up this year. “It was where I wanted to be from the beginning,” he said of free agency. “Hopefully, finish my career with this uniform.” He added that he is happy to play wherever the Mets want him — even in the outfield. “I’ve got all kinds of gloves in my locker,” he said. “Whatever they need me to be, I’m going to be that.’’

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