Belt, 26, missed two weeks with a concussion late last month. He returned last weekend, played four full games, then had to be removed from Wednesday's game with headaches. Belt did not play Thursday.
Needless to say, the Giants have to play it carefully with their first baseman if his symptoms have returned. Brain injuries are not something to take lightly. I'm sure they will be extra careful now.
Belt is hitting .237/.296/.446 (110 OPS+) with 11 home runs in 51 games this year. He also missed time with a broken thumb after being hit by a pitch. Belt broke out with a 140 OPS+ and 17 homers last year.
With Belt out, the Giants figure to play Mike Morse at first base most of the time.