The Orioles announced after tonight's game that they've optioned Arrieta to Triple-A Norfolk. The move was made to create room on the 25-man roster for left-hander Zach Britton, who will start Tuesday night against the Tigers at Comerica Park.
The Orioles won't announce the corresponding move until Tuesday. They also can make a second move to replace Miguel Gonzalez, who left the team to be with his wife for the birth of their daughter.
Arrieta allowed five runs and 10 hits in 4 1/3 innings in a 5-1 loss to the Tigers. He walked one batter, intentionally, and struck out three.
Arrieta fell behind immediately when Miguel Cabrera hit a two-run homer in the bottom of the first inning.
Arrieta has made five starts for the Orioles, allowing 19 runs and 25 hits in 23 1/3 innings. He's walked 17 batters and struck out 23.