Cobb, who has a 5-2 record with a 3.09 ERA in 14 games this season, strained his left oblique in an 11-4 win against the St. Louis Cardinals on Tuesday. The right-hander was placed on the 15-day IL retroactive to Thursday. He had expected to be able to start Monday to begin a three-game series against the San Diego Padres after going through a typical workout Saturday.
"I was fully anticipating throwing this series, but we're being pretty cautious," Cobb said following the Giants' 7-3 win against the Los Angeles Dodgers on Sunday.
Cobb said further injury to his oblique would likely result in his missing four to six weeks, prompting the stint on the IL. Manager Gabe Kapler said Cobb could return against the New York Mets at the end of June.
"We just thought it made some sense to protect him here for the long haul, take the long view," Kapler said.
Cobb had been one of the keys in helping the Giants get back on track. Since the start of May, San Francisco has won seven of the eight games Cobb started, with the 35-year-old posting a 4-1 record in those outings.
The loss of Cobb comes a day after the Giants got righty Alex Wood back Saturday from a lower back injury that kept him out since the start of June.
Right-handed reliever Keaton Winn was recalled from Triple-A Sacramento on Sunday. Wynn earned his first career save in his major league debut Tuesday, allowing one run in four innings.
Kapler did not say who would start in place of Cobb against the Padres on Monday.
"We've got enough arms to cover the next couple of games," Kapler said.