The Orioles purchased the contract of right-handed pitcher Mychal Givens. The converted infielder has never pitched in the major leagues.
Wei-Yin Chen and Miguel Gonzalez start for Frederick and Bowie on Saturday night.
Kevin Gausman gets his first start of 2015 against the Toronto Blue Jays.
Marco Estrada held the Orioles hitless through seven innings, but Baltimore nearly pulled off the comeback anyway.