Baumann was optioned to Triple-A Norfolk on Monday, Roch Kubatko of MASNSports.com reports.
The move comes as teams around the league are required to drop the number of pitchers on their active rosters to 13. Baumann's latest MLB stint lasted four days. He threw a scoreless innings of relief Sunday against the Rays in his lone appearance, dropping his ERA on the season to 4.50.