Manager Charlie Montoyo said De Leon suffered a right shoulder injury during Monday's spring game against the Tigers and is being evaluated by the medical staff, Hazel Mae of Sportsnet reports.
De Leon was down in some pain after spiking a pitch during Monday's appearances, and the specifics of the injury remain uncertain. The 29-year-old is in camp as a non-roster invitee after posting a 8.35 ERA over 18.1 innings for Cincinnati last year.