Walker's (side) MRI came back clean Tuesday, Mike Puma of the New York Post reports.
Walker left his start Monday against Atlanta with left side tightness, an issue he's apparently been dealing with for a few weeks. He hasn't been placed on the injured list, however, so the clean MRI could mean he doesn't wind up missing any starts. Walker is tentatively lined up to make his next start Sunday in Miami, but due to an off day Thursday, the Mets could get by with a four-man rotation until May 25 if the right-hander requires more recovery time.