Baumann was optioned to Triple-A Norfolk on Thursday, Roch Kubatko of MASNSports.com reports.
Baumann was called up on Sept. 7 to make his major-league debut and pitched 10 innings since, allowing 11 earned runs and maintaining a 5:6 K:BB. Though he's well-regarded within the Orioles' farm system, Baumann appeared to be overmatched in his first stint in the majors.