He was called up from the Triple-A Sacramento River Cats and made his MLB debut on June 22, 2004, as a Pinch Hitter for Bobby Crosby.

In 2005, Castro played in the Washington Nationals organization, but was suspended 105 games in July and fined an undisclosed amount for violating the steroids policy.

[1] He previously played for the Newark Bears from 2007 to 2008, being named the Most Valuable Player of the 2008 Atlantic League All-Star Game after hitting two home runs.

Castro set Revolution season records in 2010 with a .339 batting average, 37 doubles and a .437 on-base percentage, ranking second in the Atlantic League in all three categories.

His final highlight was driving in the championship-clinching run on a tenth-inning sacrifice fly during Game 3 of the Atlantic League Championship Series at Bridgeport Bluefish.