NEW YORK — Decades ago, David Stearns used to sneak into Shea Stadium to root for the New York Mets.

Now, he holds their entire roster in his hands.

Stearns was formally appointed the first president of baseball operations in Mets history Monday, taking over the hometown team he cheered as a child.

“I appreciate that they’re letting me in here without a ticket,” he said.

“The good news about Shea in the late ’90s is you had some ticket takers and ushers who were pretty sympathetic to a 13-year-old kid who just wanted to watch baseball,” Stearns said with a smile. “Only happened a couple times. May have only happened with one specific usher. But most of the time I was a legal paying fan.”

The former Milwaukee Brewers boss was introduced by owner Steve Cohen at a Citi Field news conference on the heels of a hugely disappointing season. Despite championship aspirations and a record $355 million payroll on opening day, New York dropped out of playoff contention by midsummer and finished fourth in the NL East.

“I’m thrilled to be here. This is my home. It’s nice to be back,” Stearns said. “I’ve got plenty of work to do.”

The 38-year-old executive was placed above general manager Billy Eppler and under Cohen in a working structure fairly common around baseball but new to the Mets.

A large scoreboard display in center field welcomed Stearns, who will lead a search for the team’s next manager after Buck Showalter was fired Sunday.

“I view the managerial position as one of true partnership,” Stearns said, later adding he’d be open to a first-time manager. “There’s no one I have in mind. We are going to cast a wide net. We’re going to have a real process.”

He also said he expects Pete Alonso to be New York’s first baseman on Opening Day next year — the All-Star slugger has been the subject of trade speculation because he’s eligible for free agency after the 2024 season.

“Pete is a great player. He is also good in the clubhouse. He is also homegrown. All of that matters,” Stearns said. “Pete’s an important member of this team, he’s an important member of this organization and I think we’re really fortunate to have him.”

Cohen had been seeking a president of baseball operations to oversee the entire department since buying the club in November 2020. Several attractive candidates, including Stearns, were unavailable during a three-year process that Cohen called “sort of dog years.”

“I’m really excited by this,” Cohen said. “You know, I’ve been really patient looking for the right person. As David and I got to know each other, I mean, it’s clear that we’re aligned in our thinking. We get along very well.”

Stearns grew up a Mets fan in New York City and even interned for the team early in his career. He said he and Cohen spoke about a dozen times on the phone and met face-to-face four times for three-to-six hours each, including a pivotal dinner with their wives that convinced Stearns working for the Mets could be the right fit.

As speculation increased over time that he would ultimately land this job, Stearns said he and his wife had to calm his excited mother, Susan, before finally getting to call her a couple of weeks ago and tell her “this was really happening.”

“It’s meaningful for me, it’s cool for me that our kids get to grow up Mets fans now. That we get to share that. That we get to live this journey together and they get to experience a little bit of what I experienced,” said Stearns, a Harvard graduate. “I grew up listening to Gary Cohen and Bob Murphy and Ed Coleman every summer. I’ve ridden the rollercoaster of disappointment and hope, along with every other Mets fan.

“I feel very fortunate and privileged to be here right now. I understand this doesn’t happen, right? You don’t grow up a rabid fan of a team and then one day get to stand here at a press conference talking about leading that team,” he added. “And so the fact that it has happened to me, I recognize how incredible that is.”

Stearns worked in the commissioner’s office at Major League Baseball from 2008-11. He was Cleveland’s director of baseball operations in 2012 and an assistant GM with Houston from 2013-15 during a successful rebuild.

After taking over the Brewers, he enjoyed a winning run while leading Milwaukee’s baseball operations department from September 2015 through the 2022 season before stepping down and moving into an advisory role.

Milwaukee came within one victory of the World Series in 2018 and returned to the playoffs each of the next three seasons. The Brewers won NL Central titles in 2018 and 2021, and another one this year. Stearns agreed to join the Mets last month, and his contract with the Brewers expired Sunday.

“I need to get under the hood a little bit, talk with our group, understand internally here what we think we do well and where we think there are areas for improvement,” Stearns said.

“Can you do what the Brewers have done here in New York? I think we can develop good starting pitching here. Absolutely. But it’s going to look different than the way Milwaukee has done it. It has to. No two organizations are the same,” he added. “We have to create our own blueprint here and I think we will.”