Bierd's best season in the Tigers organization came in 2007, when he pitched for the Single-A West Michigan Whitecaps and the Double-A Erie SeaWolves. Pitching in a total of 42 games, 3 of which were starts, Bierd went 4-3 with a 2.93 ERA.
On December 6, 2007, Bierd was selected by the Baltimore Orioles as the third overall pick in the major league phase of the Rule 5 draft. Bierd made the Orioles 2008 opening day roster as a relief pitcher. On April 2, 2008, Bierd made his major league debut against the Tampa Bay Rays, and pitched two scoreless innings. and was later placed on the 15-day disabled list