Ryan Mount Castle of the Orioles was placed on the 15-day injured list due to a wrist injury that didn't improve with treatment despite efforts to keep him active his performance has declined since the All-Star break contributing to the Oriol struggles to distance themselves from the Yankees in the AL East since Ryan Mount Castle's injury Ryan o'hern has started most of the Orioles games at first base due to his strong defense and solid hitting however o'hern excels more against left-handed pitchers which could lead manager Brandon Hyde to use a platoon strategy Jonathan Rivera though not a power hitter has been reliable against lefties while Rivera isn't a standout option he could serve as a viable platoon player until Mount Castle returns