The Red Sox optioned Gasper to Triple-A Worcester on Sunday, Tim Healey of The Boston Globe reports.
The 30-year-old had received fairly regular playing time between catcher and designated hitter since about mid-May, but his .486 OPS in 17 games this month will result in him being demoted. Romy Gonzalez (shoulder) was reinstated from the injured list and will take over Gasper's spot on the 26-man active roster.