Mengden will be out of his walking boot Monday, Susan Slusser of the San Francisco Chronicle reports.
Mengden underwent surgery in February after fracturing a bone in his right foot while tossing a bullpen session. Shedding his walking boot will be the first major step in his recovery process, which still remains without a firm timetable. The 23-year-old was in contention for the fifth starter role before he was sidelined, but the injury now leaves him with work to do once he's fully recovered.