The moves were made to clear a roster spot for rookie right-hander Kevin Gausman, the fourth overall pick in the 2012 draft. He is being promoted from Double-A Bowie to make his major league against the Blue Jays on Thursday night.
The 22-year-old Gausman has only 13 games of professional experience. He went 2-4 with a 3.11 ERA at Bowie this season, striking out 49 and walking five in 46 1-3 innings.
Arrieta is 1-1 with a 6.63 ERA in four starts this season. He went 3-9 with a 6.20 ERA last year.
Burnett pitched in two games for the Orioles, allowing three runs and four hits in 1 1-3 innings.