The injury happened in an accident Saturday at Cespedes' ranch in Florida. Per Van Wagenen, Cespedes was not on a horse when he suffered the injury; he "stepped in a hole" and had a "violent fall." He is undergoing evaluation in New York.
Cespedes, 33, has missed much of the last two seasons because of injuries. Hamstring problems were the main reason he missed half the 2017 campaign, and heel surgery limited him to 38 games in 2018.
"We expect him to be an MVP-caliber player when he comes back," Van Wagenen told reporters in February. "And I know he does as well."
Cespedes has yet to make his 2019 debut as the Mets have sputtered out of the gate. The team is 20-25, 6.5 games back of the first-place Philadelphia Phillies in the National League East.
Jeff McNeil has started in Cespedes' place throughout the year and will remain in left field for the foreseeable future.