Matusz struck out five, while walking one and allowing six hits over five innings.
Matusz was 7-0 with a 1.55 ERA in eight starts with Bowie. Before being promoted from Class-A Frederick, he was 4-2 with a 2.16 ERA in 11 starts.
Matusz was the Orioles' first-round pick (fourth overall) in the 2008 draft out of the University of San Diego.
The Orioles optioned righty Kam Mickolio to Triple-A Norfolk. He was 0-0 with a 0.00 ERA in 4 2/3 innings over four relief appearances with Baltimore.
Information from The Associated Press was used in this report.