The Red Sox optioned Gamboa to Triple-A Worcester on Monday.
After being recalled from Triple-A last Wednesday, Gamboa made two appearances out of the Red Sox bullpen, giving up two earned runs in 3.1 innings. He'll head back to the minors to clear room on the active roster for left-hander Patrick Sandoval (biceps), who was reinstated from the 60-day injured list and is expected to join the rotation later this week.