In December 2007, the Royals signed Greenberg to a minor league contract for 2008. Unable to gain a spot in the Triple-A Omaha Royals outfield, Greenberg was granted free agency by Kansas City. After a brief stint with the Independent Bridgeport Bluefish near his hometown of Guilford, in which he batted .289 with a .450 on-base percentage, Greenberg signed a contract with the Los Angeles Angels of Anaheim and was assigned to the Double-A Arkansas Travelers. There, he batted .271 with a .361 on-base percentage, and 16 steals in 262 at-bats.