The Rays placed De Leon (elbow) on the 10-day injured list Thursday, Steve Carney of Sports Radio 620 WDAE reports.
De Leon is a year removed from Tommy John surgery and has progressed to the point of facing hitters in live batting practice. He could soon be ready to test his elbow in a simulated game, but the right-hander is realistically at least a couple months away from being activated from the IL. De Leon could eventually be transferred to the 60-day IL to free up a spot on the 40-man roster.