The 6-foot-6-inch, 235-pound Masterson was drafted by the Red Sox in the second round (71st overall) of 2006 amateur entry draft. The 22-year-old righthanded pitcher went 4-3 with a 4.34 ERA in 10 starts at Double-A Portland in 2007. At Single-A Lancaster, Masterson went 8-5 with a 4.33 ERA in 17 starts last season.