Belt was already on the disabled list and will have surgery, which involves the insertion of two pins, on the thumb Tuesday. The pins will be removed after four weeks, and Belt will then go through two weeks of rehab.
"When they take the pins out, you'll have a better idea of where you're at, how much baseball activity you can do and how much you can ramp up your rehab," Bochy told the San Francisco Chronicle. "He'll definitely have to play some games in the minor leagues."
Belt is hitting .264 with nine home runs and 18 RBI for the Giants, who lead the National League West with a 24-14 record.