Cobb is dealing with a left hamstring issue but is optimistic he can avoid a stint on the injured list, Evan Webeck of The San Jose Mercury News reports.
It was originally reported that he was scratched from Friday's scheduled start with a back issue. Cobb said his left hamstring tightened up earlier this week in Philadelphia and he had sharp pain that kept him from sleeping that night. He said he feels better now but it's unclear when he will make his next start.