Jack was drafted in the 3rd round by the Detroit Tigers in the 2001 amateur draft. From 2001 to 2006, Jack steadily progressed within the Tigers organization from Single to Triple-A.  Jack made his major league debut on May 26, 2005 against the Kansas City Royals.

On August 12, 2007 Jack was traded to the Oakland Athletics and subsequently promoted to the major league roster.  In 2008 Jack was the starting 3B for the Athletics, playing in 143 games.

At the University of Minnesota, Jack earned Big Ten Player of the Year and All-American honors in 2001.