De Leon (elbow) was activated from the 60-day injured list and optioned to Triple-A Durham on Wednesday, Juan Toribio of MLB.com reports.
De Leon has been limited to rehab action since undergoing Tommy John surgery last March. The 26-year-old has yet to establish himself at the big-league level, recording a 6.86 ERA in just 19.2 innings of work, and he won't get the chance to improve those numbers just yet. He did have at least a small amount of hype as a prospect thanks to a strong changeup, so he could make an impact on the Rays' roster at some point in the second half, either as a starter or a multi-inning relief arm following one of the team's many openers.