Cobb has been out since June 15, when he was struck on the side of the head by a line drive. Since then, he has been dealing with concussion symptoms and vertigo. However, a blister on the index finger of his pitching hand that has caused a setback in his return.
The Rays originally sent Cobb on a rehab assignment on July 23, but his outing was cut short due to the blister. He tried a number of remedies to fix the ailment, but could not throw without a protective covering on the blister until Wednesday.
Cobb, 25, was one of the Rays' best pitchers before going on the disabled list. Over 13 starts, he has a 3.01 ERA and 1.159 WHIP.