Cobb had the bullpen session before Friday night's game against the Chicago White Sox. There is no timetable for when Cobb will pitch in a game.
"The bullpen went great," Cobb said. "It felt like I had before I got injured. Surprising because it usually feels a little awkward out there when you haven't been on the mound for a while. Getting on the mound is, obviously, a step in the right direction. I don't think we're extremely close, but we're a lot faster along than we expected."
Cobb said his vertigo symptoms have improved over the past week.
"It's a little bit better, but it should within the next couple weeks, listening to what the doctors say, a drastic improvement in where we are right now," Cobb said.
Cobb was struck in the right ear by a ball hit by Kansas City's Eric Hosmer on June 15 and was hospitalized overnight after being carted off the field.
"Anytime he's making some progress, that's great," Tampa Bay manager Joe Maddon said.