The Mariners optioned Locklear to Triple-A Tacoma on Monday.
Locklear will cede his spot on the 26-man active roster to second baseman Jorge Polanco (hamstring), who was reinstated from the 10-day injured list in a corresponding move. The demotion doesn't come as a major surprise, as Locklear logged just three plate appearances while starting in only one of the Mariners' last six games following Ty France's return from the IL last Tuesday.