The start will be first for Slowey since July 8. He started 14 games for Miami last year and went 3-6 overall with a 4.11 ERA.
Hand fell to 1-11 as a starter when he lost Monday to Washington. He'll return to a long-relief role, manager Mike Redmond said Wednesday.
Hand made two starts filling in for right-hander Jacob Turner, who is on the disabled list with a shoulder injury. Turner is scheduled to throw a bullpen session Friday.