Kellen was a standout player at Dunbar High School in Baltimore, MD. He led the state (MD) in hitting in 1998 as a Senior (.698). Received all city and all metro honors as well for his play as an Outfielder and Pitcher. He earned a full athletic scholarship to Alabama A&M Univ., But then returned home to play at Baltimore City CC.
During the summer of “99” Kellen signed as a free agent with the then Anaheim Angels Organization. During his time with the Angels, Kellen participated in the Pioneer League, Fall Arizona Instructional League and the Arizona League