You'll recall soon after the injury that Harvey felt he could rehab the injury and that he would be prepared to pitch this April, despite team reports that surgery would ultimately be required. He later stated it took a bit of time for him to grasp the reality of the situation and opted for surgery that would rule him out for the entire 2014 season. The Mets couldn't force Harvey to have that surgery. As it turns out, they can tell him where to rehab from it either.
In a decent piece of digging by the NY Post's Ken Davidoff, it appears that Harvey can return to New York and stay with the team if that's what he decides to do. Davidoff quotes the following excerpt from the collective bargaining agreement:
“A Club may direct a Player to perform prescribed rehabilitation work for an injury
during the championship season at a rehabilitation facility at one of the following three
sites: (a) in the Club’s home city; (b) on the road with the Club; or (c) at the Club’s
spring training facility; provided, however, that a Club may not direct that a Player
perform prescribed rehabilitation work for an injury at its spring training facility for a
period of more than 20 days without the Player’s written consent.”
This isn't an issue to date, but Harvey hasn't been shy about his desire to remain with the team. If he does so, it would be a deviation from standard operating procedure for the Mets, who usually have their walking wounded rehab in Florida. Its a bit more important in Harvey's case, as his high profile night life and position with the team could serve as a distraction if he doesn't become more tactful with the media. That however remains to be seen, but it remains clear that Harvey has the leverage in this instance and will ultimately decide where he rehabs from his season ending Tommy John Surgery.