Gallen (elbow) was activated off the 10-day injured list ahead of his scheduled start Thursday against the Giants.
Gallen's season has been disrupted twice already, first by a hairline fracture in his forearm in late March and then by an elbow sprain in mid-May. He was only able to make five starts between the two injuries but recorded a strong 3.04 ERA, a number which exactly matched his FIP. He may not be asked to pitch particularly deep in Thursday's contest, as he threw just 46 pitches in his final simulated game Saturday.