Kelly grew up in Springfield, Virginia and attended Paul VI Catholic High School.
He was named a freshman All-American by the Collegiate Baseball Newspaper after going 5–3 with a 2.91 ERA and 38 strikeouts in 34 innings pitched over 24 relief appearances.
[7] After signing with the team he was assigned to the Arizona League Indians and had a 2.08 ERA and struck out 25 batters in 17+1⁄3 innings pitched.
[11] In 48 appearances split between Akron and the Triple-A Columbus Clippers, Kelly pitched to a combined 5–2 record and 2.04 ERA with 75 strikeouts and 4 saves in 57.1 innings of work.
[13] On April 28, Kelly recorded the final out in a 3–2 victory over the Chicago White Sox to earn his first career save.