Castro (shoulder) made his second rehab appearance in the rookie-level Arizona Complex League on Saturday, striking out four and allowing one hit and no walks over two scoreless innings.
Castro was placed on the Diamondbacks' 15-day injured list April 23 with right shoulder inflammation but looks to be closing in on a return after turning in a pair of scoreless appearances in the ACL. According to MLB.com, manager Torey Lovullo previously said that the Diamondbacks are targeting this upcoming Wednesday for Castro's return from the IL, but that date could be pushed back if the organization first wants him to get in some work with a higher-level affiliate.