De La Rosa (elbow) began a rehab assignment with Triple-A Reno on Thursday.
De La Rosa suffered a setback a couple weeks ago when he felt tightness in his injured forearm, but fortunately that was only minor, as he was able to get back on the mound just a couple weeks later. De La Rosa has worked almost exclusively as a starter since joining the Diamondbacks, but he threw just one inning Thursday and could work in a bullpen role for the rest of this season given the amount of time he would need to build up his pitch count in order to start.