Mets' Pete Alonso will face a big contract decision. How did Atlanta's Matt Olson make his? 

ATLANTA — Sometime in the next 15 months or so, Pete Alonso will make one of the biggest decisions of his life: where to play the next phase — and perhaps the majority of — his career.

Whether he signs a contract extension with the Mets or picks them or another club upon reaching free agency after next season, Alonso’s choice looms large in the context of the team, too, given all that he has done and the leaderboards he has climbed in just under five full seasons in the majors.

How does a franchise cornerstone first baseman make such a call? Matt Olson, an NL MVP candidate and Atlanta slugging staple, whose eight-year, $168 million contract signed before the start of last season is one of the most recent barometers for first baseman megadeals, would know.

Among the reasons Olson decided to commit, he said: the fact that he thought the offer was strong, the caliber and reputation of Atlanta as an organization and the straightforward approach by general manager Alex Anthopoulos. And it helped that he grew up outside Atlanta as a fan of the team — a dynamic not in play in the case of Alonso, a Tampa native who has embraced New York.

“Obviously, there’s a ton of factors,” Olson said in an interview with Newsday on Monday. “Hometown, obviously a really good team that had just won a World Series, I had heard a bunch of good things about the organization beforehand. Signing something long-term was something that I was open to, even in Oakland.

“For me personally, it was never really about breaking the bank. I wanted to have some security and go out and play some baseball. When all those things happened and the offer came so quickly, I decided why not?”

Olson, just eight months older than Alonso, could have taken a year-to-year approach and reached free agency after this season. He would be about to cash in, too, based on his monster numbers, including a major league-leading 43 homers and 108 RBIs entering the week.

Even though he didn’t prioritize maximizing the money, Olson said he was wowed when Atlanta threw such a sum at him in March 2022. Mere hours earlier, it had acquired Olson via trade with the Athletics.

“I thought it was a fair offer. I don’t think anybody was taking either side for getting an advantage,” he said. “It was super-honest and fair, and that was part of the reason I ended up doing it. I appreciated how Alex can be a little to the point and honest, and I like that.”

Alonso has declined to publicly discuss his Mets future, including the state or even existence of negotiations. He said on Aug. 1: “We’ll see what happens. I don’t necessarily know what the future holds. But as long as I’m here, you’re going to get the best from me every single day.”

Their circumstances differ in a variety of ways, but here is a look at some of the factors:

 n  Olson was two seasons away from free agency, which left him with less leverage than will be enjoyed by Alonso, who will have one season to go if he and the Mets engage in the coming months. Olson’s 2022-23 salaries, sans an extension, would have been limited by baseball’s arbitration system. This is a point in Alonso’s favor.

 n  Olson’s pact covers his age-28 through age-35 seasons. Alonso, if he reaches free agency, would play on a theoretical eight-year deal from 30 to 37. That works against him, especially at a position at which even the best hitters tend not to age gracefully.

 n  Olson (134 OPS+ before he signed) and Alonso (139 OPS+) are similarly productive as hitters. Olson is regarded as a better defender, having won two Gold Gloves with Oakland, though Alonso has rated better in a couple of key defensive stats this year.

 n  Last offseason, after Olson made his commitment, the market yielded several extremely long contracts that, naturally, came with gigantic dollar figures. Manny Machado (11 years), Rafael Devers (11), Trea Turner (11), Xander Bogaerts (11), Aaron Judge (nine) and Brandon Nimmo (eight) all got deals longer than anticipated. If that trend keeps up, Alonso would stand to benefit.

For Olson, it all worked out more than fine. For Alonso, as he said, we’ll see what happens.

“I never really played for that, to see how much I can make,” Olson said. “Obviously, it’s a lot of money, life-changing money. But it felt like a fair offer to me based on things I had done in the past — that’s what you get paid on — and the projections. It was an easy decision for me.”

By Tim Healey

timothy.healey@newsday.com@timbhealey

Tim Healey is the Mets beat writer for Newsday. Born on Long Island and raised in Connecticut, Tim has previously worked for the South Florida Sun Sentinel, the Boston Globe and MLB.com. He is also the author of “Hometown Hardball,” a book about minor league baseball in the northeast.