Castillo (forearm) resumed a minor-league rehab assignment last week and has made two appearances, working two innings and giving up an earned run on two hits while striking out five.
Castillo has been on the shelf since late February with a left forearm flexor strain. He initially seemed to be trending toward a late-June return from the 60-day injured list, but a potential reinstatement was put on hold after he experienced renewed soreness in his forearm. After just over a month-long shutdown period, Castillo is apparently feeling healthy again and could be on track to join the Padres at some point in August if he steers clear of any further setbacks. Castillo is currently pitching with the Padres' High-A affiliate in Lake Elsinore, but he should shift his assignment to Triple-A El Paso within the next week or so.