 A graduate of Hackettstown High School, Kimball first attended St. John's University in New York, before transferring to Centenary College of New Jersey and was selected by the Nationals in the 12th round of the 2006 amateur draft.After being drafted by Washington, Kimball began his minor-league career pitching for the Vermont Lake Monsters in the short-season New York–Penn League.In five starts and eleven relief appearances, he pitched 34 innings, compiling a win-loss record of 1-4 and an ERA of 5.82.