Seattle transferred Criswell (shoulder) to the 60-day injured list Friday.
The move opens up a spot on the 40-man roster that the Mariners needed for Miles Mastrobuoni, whose contract was selected from Triple-A Tacoma after Julio Rodriguez (concussion) was placed on the 7-day IL. Criswell was diagnosed with a Grade-1 pectoral strain in mid-June but has since been tagged with a shoulder strain. The move to the 60-day IL doesn't change his projected return for early August, though a clearer timeline won't be established until Criswell embarks on a rehab assignment.