Ross threw a bullpen session consisting of 30 pitches on Wednesday. Of course, there's nothing wrong with his right arm or shoulder. But he's not to the point where his left shoulder feels good enough to return.
"It was just nice to get on the mound again after missing a week," Ross said Friday. "Right now, I'm just working with the training staff to strengthen [the shoulder]."
Ross will continue to keep his arm in shape until he reaches the point where he can take batting practice and test the left shoulder. He's even talked with hitting coach Phil Plantier about his swing.
"The big test will come when I'm able to swing a bat," Ross said. "I've already talked to [Plantier] about it and about cutting down on my swing. We've got to get to a point where we feel good with it."
Ross, who was 0-1 with a 3.86 ERA in his first three starts, has been replaced by Friday's starter, Andrew Cashner, in the rotation. Cashner makes his second start at Petco Park against the Giants.
Corey Brock is a reporter for MLB.com. Keep track of @FollowThePadres on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.