Gsellman (hamstring) is slated to begin a rehab assignment with Double-A Binghamton on Thursday.
Gsellman has been slowly working his way back from a left hamstring strain suffered during a June 27 outing and finally seems able to return to live action. It's unclear how many rehab appearances the right-hander will require before he's able to return to the Mets, but he should slot back into the injury-hampered rotation upon his activation. Gsellman racked up a 6.16 ERA over 17 games (14 starts) and a .303 BAA prior to being sidelined.