Cespedes has not played this season after undergoing surgery to remove calcification on both of his heels last year. Those surgeries were expected to keep him sidelined for at least half of this season, but this latest setback puts Cespedes' entire season in jeopardy.
General manager Brodie Van Wagenen on Monday said the team learned Saturday night that Cespedes had broken his right ankle in a fall on his ranch in Port St. Lucie, Florida, where the club's spring training complex is located, and suffered multiple fractures in the accident.
"He had a violent fall in which he stepped in a hole and put his leg and foot in a difficult position," Van Wagenen said.
The 33-year-old Cespedes enjoys riding horses. He told the team he did not fall off a horse, but Van Wagenen -- declining to offer more specifics -- said the injury was not baseball-related.
That could affect how much money the Mets can recoup in insurance on Cespedes' contract or whether he was involved in an activity prohibited by the deal's guarantee language. The two-time All-Star, who helped lead the team to the 2015 World Series and a 2016 playoff appearance, has played only 119 games since signing a $110 million, four-year deal before the 2017 season.
Van Wagenen, who was with the Mets in Miami over the weekend, said he left the club to go see Cespedes on Sunday and make sure he receives the best medical care. The outfielder was in New York being evaluated at the Hospital for Special Surgery, and Van Wagenen said it was too soon to know how long Cespedes' latest injury will keep him out.
In other news, Robinson Cano was out of Monday's starting lineup -- for multiple reasons, according to Callaway -- after failing twice to hustle last weekend.
Callaway said he spoke with Cano several times over the past few days and that Cano was on the bench against Nationals left-hander Patrick Corbin because Cano has struggled against lefties, "he understands that it's unacceptable to not run balls out" and the 36-year-old second baseman could use a day off.
Some fans booed when Cano came up as a pinch-hitter in the sixth inning. He was cheered after legging out a crisp double.
After the Mets' 5-3 victory, Callaway was told it was the fastest Cano has run from home to second on a double in three years, according to Statcast data.
"It should have been. It better have been,'' Callaway said, drawing chuckles. "I guess he got the hint.''
Right-hander Seth Lugo, one of New York's most valuable and reliable relievers, was placed on the 10-day injured list with tendinitis in his pitching shoulder. The team selected the contract of left-hander Hector Santiago from Triple-A Syracuse and transferred infielder Jed Lowrie to the 60-day injured list.
Van Wagenen said the move won't affect the timetable for Lowrie to make his Mets debut after signing a $20 million, two-year contract in the offseason. Lowrie sprained his left knee capsule early in spring training and then hurt a hamstring this month while on his rehab assignment, the Mets said.
New York (20-25) had lost a season-worst five straight and 21 of 32 overall heading into the opener of a seven-game homestand Monday night against National League East rival Washington. Missing injured slugger Michael Conforto (concussion), the listless Mets were swept in three games at lowly Miami over the weekend and totaled only three hits in consecutive shutouts Saturday and Sunday.
With questions intensifying about Callaway's job security in his second season as manager, the Mets held a meeting Monday with players and coaches to declare support for Callaway and his staff.
"Mickey is our manager now. Mickey is our manager going forward," Van Wagenen said at a news conference attended by chief operating officer Jeff Wilpon.
"We're not looking to blame a manager," the GM added. "He has our full support to lead this team for the foreseeable future."
Van Wagenen said the Mets haven't met their expectations so far, but they know they can play better.
"The finger-pointing is not going down the chain of command to the players or the coaches. We built this team in the front office. We believe that this team has the ability to contend, the same way we said that in the offseason loudly and proudly. The accountability that will ultimately fall on this team, I want to place on my shoulders," Van Wagenen said.
"At the end of the day, this is our team. We're proud of it, we believe in it," he added.
Callaway said he appreciated the support but never felt he didn't have it.
"I've never looked over my shoulder," he said. "We have to climb out of it, and I believe we will."
After putting Lugo on the injured list, New York switched course a bit and chose Wilmer Font (0-1, 9.95 ERA) over fellow right-hander Drew Gagnon (1-0, 4.09) to start Monday night in place of injured Jason Vargas. Callaway said with Lugo out, the team was confident in Gagnon's ability to help protect a potential lead out of the bullpen.
Van Wagenen also said Conforto has been symptom-free for the past three days. The outfielder is on the seven-day concussion list.
The Associated Press contributed to this report.
Mets GM: Cespedes fractured ankle in ranch accident
Mets GM Brodie Van Wagenen says Yoenis Cespedes suffered an accident at his Florida ranch and fractured his ankle.