Crosby chose not to sign with the Angels, however, opting instead to play college baseball for California State University, Long Beach.

In 2004, his first full MLB season, he took over the Athletics' shortstop duties from 2002 American League Most Valuable Player Miguel Tejada, who signed with the Baltimore Orioles as a free agent.

[1] These numbers earned Crosby Rookie of the Year honors, the sixth Athletics player to do so after Harry Byrd (1952), José Canseco (1986), Mark McGwire (1987), Walt Weiss (1988), and Ben Grieve (1998).

[1] In addition to becoming the sixth Athletics player to be named Rookie of the Year, he was the second shortstop in a row to win the award (after Ángel Berroa of the Kansas City Royals).

He was also the eighth shortstop in 22 seasons to earn top rookie honors, the others being Cal Ripken Jr. (1982), Ozzie Guillén (1985), Walt Weiss (1988), Pat Listach (1992), Derek Jeter (1996), Nomar Garciaparra (1997), and Berroa (2003).

[2] Due to the signing of free agent shortstop Orlando Cabrera prior to the 2009 season, Crosby was moved into a utility infielder role.