Castillo (shoulder) is set to begin a rehab assignment in coming days with High-A Everett, Daniel Kramer of MLB.com reports.

EDGE Analysis

Castillo has been on the shelf since July 28, with his stint retroactive to two days prior. The right-hander reliever will likely only need a couple of rehab appearances before being deemed ready for activation, and he'd be eligible to return as soon as Wednesday.