Cowser is out of the lineup for Monday's game against the Red Sox.
Cowser will join fellow left-handed hitters Samuel Basallo (shoulder), Dylan Beavers and Jackson Holliday on the bench while the Red Sox send southpaw Payton Tolle to the bump for the series opener. Leody Taveras will draw the start in center field Monday in place of Cowser, who went 1-for-10 with one walk and one stolen base during the Orioles' three-game sweep of the Astros over the weekend.