His manager addressed his problems before Sunday's series finale in Pittsburgh, saying he thinks the issue has more to do with Belt than opposing pitchers.
"He's out of sync up there at the plate with his timing," Bruce Bochy said. "His confidence is shaken a little bit. Those are tough at-bats he had [Saturday]. You could tell he wasn't seeing the ball very well.
"He's not one that usually chases pitches very often, and he was going out of the zone more than we're accustomed to. We'd like to get him back to being a little more patient and taking his walks."
Belt came into Sunday with a .255 average, four home runs and 30 RBIs. He's off to a slow start in June, however, hitting .235 (4-for-17) with eight strikeouts already in the month.
Bochy expressed confidence in Belt, though, saying he doesn't expect his role to change much for the second half.
"We're in a pretty good position right now," Bochy said. "I think as we open up the second half, you'll pretty much see the same lineups you've seen."