This season, the 35-year-old Vogelsong has pitched to a 7.19 ERA in nine starts. He was, however, quite effective in 2011 and 2012. As for replacing Vogelsong, the Giants have time to make a decision, as they won't need a fifth starter until next Tuesday.
Right-handed reliever Santiago Casilla has also been placed on the DL by the Giants. Casilla, who's been troubled by lingering knee discomfort, has a 1.89 ERA in 21 appearances this season. In parts of four seasons with the Giants, he's pitched to a 2.19 ERA, 1.18 WHIP and 2.00 K/BB ratio across 189 1/3 innings.