Less than two years later, Callaway no longer has a job.
The Mets on Thursday cut ties with the second-year manager despite an 86-76 season highlighted by a midsummer surge that put them in the postseason hunt.
Ultimately, New York fell short of October baseball, and it cost the 44-year-old Callaway his job.
"I feel unfulfilled. I feel we left some games on the field that we should have won, and we didn't fulfill what we really had as a goal, which was get to the postseason," chief operating officer Jeff Wilpon said on a 30-minute conference call with reporters. "We're not playing October baseball, and that's what it's about."
With the Mets holding organizational meetings at their spring training facility in Florida this week, general manager Brodie Van Wagenen and Wilpon flew to Callaway's hometown, also in Florida, to meet with him in person Thursday morning and exchange thoughts.
After the meeting, they told Callaway of their decision to let him go, and that he was a "true gentleman," Wilpon said.
"We want to thank Mickey for his consistent work ethic and dedication over the last two seasons and I'm certain these characteristics will serve him well in his next opportunity," Van Wagenen said in a statement. "A decision like this is never easy, however, we believe it is in the best interest of the franchise at this time."
"While I am disappointed by the decision to move on, I am grateful to have been part of such a storied franchise," Callaway said as part of a statement Friday. "I am thankful for the hard work and support of my coaching staff, the players and all of those working behind the scenes in roles that made our jobs and lives easier.
"I'm proud of what we accomplished together. Many players got better, our team improved, and the Mets are in a better spot today to be a World Series contender."
The Mets are the seventh team seeking a new manager this offseason, joining the Angels, Cubs, Giants, Padres, Pirates and Royals.
New York hired Callaway in October 2017, tasking the former Cleveland Indians pitching coach with turning around a team that finished with 70 wins its previous season under Terry Collins.
The immediate results were strong.
New York raced out to an 11-1 record in Callaway's first season, but besieged by injuries, the Mets went 5-21 that June and never could get back in the race, finishing 77-85 and 13 games back in the National League East.
When the Mets hired agent-turned-GM Van Wagenen last October, he said Callaway's job was safe.
With expectations high, New York struggled in the first half of 2019, falling 11 games under .500 on July 11 as big offseason acquisitionsRobinson Cano and Edwin Diaz looked nothing like the players Van Wagenen had hoped for.
The hot seat seemed to affect Callaway, who cursed at a Newsday reporter following a tense postgame news conference in June, during which the manager repeatedly was asked about a bullpen decision. He later apologized.
Plenty of Callaway's pitching moves -- not to mention other substitutions -- came into question as well.
"I put my heart and soul into this team, into this game, every single day, and I believe in those players," Callaway said Saturday. "I make unpopular decisions every day, whether it's unpopular to you guys or the players. And every decision I make is going to be unpopular to somebody. But I make decisions based on trying to win games and trying to keep these guys motivated to win as many games as they possibly can. And I think that in the end when you look back on it, our players played hard and continue to play hard for a reason. And I'm proud of that."
Soon after the June confrontation, the Mets took off, winning 15 of 16 games during a torrid stretch from July 25 to Aug. 10 that saw their record go from 46-55 to 61-56. With NL home run leader Pete Alonso and ace Jacob deGrom leading the charge, New York marched into the postseason hunt and remained there until the final days of the regular season.
They ultimately finished with an 86-76 record, a nine-game improvement from Callaway's first season. But considering the seasons Alonso and deGrom had, along with those of Jeff McNeil, Michael Conforto, Seth Lugo and a host of other players, some viewed it as a disappointment.
The Mets front office apparently agreed.
New York went 163-161 under Callaway. On the final day of the season, Callaway said he had been packing up his New York apartment since last week and planned to spend 19 hours driving home to Florida on Monday and Tuesday.
He said he'd had no in-depth discussions with the front office about his future but felt no anxiety, because he "left everything on the field."
"There's conversations that I've had with players that I'd like to have another chance at, but I learned from them," Callaway said the previous day. "There's all kinds of things that you look back on and you try to self-reflect on and want to improve upon."
The Associated Press contributed to this report.
Howard: Callaway firing not all about wins and losses
Ryan Howard breaks down the Mets' decision to fire manager Mickey Callaway after two seasons.