dull made his professional debut that season with the azl athletics and he was promoted to the vermont lake monsters in july. in 31.2 total relief innings pitched between the two teams, he was 5-1 with a 2.56 era. in 2013, he played for the beloit snappers, stockton ports, and midland rockhounds, compiling a combined 2-5 record and 2.40 era in 45 total relief appearances, and in 2014, he pitched with midland, going 5-5 with a 2.88 era in 40 relief appearances. dull spent 2015 with midland and the nashville sounds, pitching to a combined 3-2 record and 0.74 era in 61 innings pitched in relief.