Entering, Fields was ranked as the fourth-best prospect in the White Sox organization and the 95th-best prospect in Major League Baseball by Baseball America. He hit safely in 14 straight games from August 6 – August 21 for the Birmingham Barons, tied for the eighth-longest streak in the Southern League. Prior to the season, Fields was once again ranked as the fourth-best prospect in the White Sox organization by Baseball America. He homered in four consecutive games from May 11 – May 14 with the Charlotte Knights, and was selected to play in the All-Star Futures Game at Pittsburgh's PNC Park. Fields made his major league debut on September 13,, but did not record his first major leagueat-bat until September 18. In that game against the Detroit Tigers, Fields hit a pinch-hit home run off Detroit's Jamie Walker. He became the third player in White Sox history to hit a home run in his first major league at-bat, joining Carlos Lee and Miguel Olivo as the only other White Sox to do so. Fields entered the season ranked as the second-best prospect in the White Sox organization and the 45th-best prospect in Major League Baseball by Baseball America. Although he started the season at Triple-A Charlotte, he was called up to the White Sox after a season ending back injury to third basemam Joe Crede. He recorded his first multi-home run game on August 10 against the Seattle Mariners, hitting both off starterJarrod Washburn. On August 26,, Fields made his first start in left field, though he only played 21 games at that position before being moved back to third base. Fields ended his first season as a Major Leaguer by hitting a promising.244, 23 home runs, 67 RBI, and an OPS of.788 in 100 games. His 23 home runs tied him with Bill Melton for 3rd most home runs by a White Sox player in their rookie season, Melton did that in 157 games. Fields received one third-place vote for AL Rookie of the Year. Entering spring training for the season, Fields was expected to be the starting third baseman, with Joe Crede likely traded. However, Crede arrived at camp fully recovered from his injury and White Sox general manager Kenny Williams was said to be unsatisfied with the trade offers. This resulted in Crede being given the starting job and Fields once again beginning the season in Triple-A Charlotte. Fields had a disappointing, injury-riddled season with the Knights, in which he regressed to a.246 batting average and.772 OPS. On July 25, 2008, he was called up to play with the White Sox after Crede was put on the 15-day disabled list. Fields underwent arthroscopic knee surgery at the end of the 2008 season, and was the White Sox's starting third baseman in until Gordon Beckham was recalled from Triple-A Charlotte on June 4 and took the position. On July 23, 2009, in a game against the Tampa Bay Rays, Fields hit a grand slam in his first plate appearance of the game. This would later end up being the game-winning home run in Mark Buehrle's perfect game over the Tampa Bay Rays, winning 5–0. Fields also caught the final out of the perfect game, a groundout to White Sox shortstop Alexei Ramírez. Six days later he would be demoted to Triple A Charlotte to make room for newly acquired Mark Kotsay.
Kansas City Royals
On November 6, 2009, Fields, along with Chris Getz, was traded by the White Sox to the Kansas City Royals in exchange for Mark Teahen. He played in 13 games for the Royals, hitting.306 during the 2010 season.
On December 20, 2010, Fields was signed to a minor league contract by the Pittsburgh Pirates. However, on March 28 he was traded by the Pirates to the Colorado Rockies, at the conclusion of spring training, for either a player to be named later or cash considerations. He recorded a.365 batting average with the Triple-A Colorado Springs Sky Sox, before being released on June 28, in order to pursue a career in Japan.
Yomiuri Giants
Fields signed with the Yomiuri Giants of Nippon Professional Baseball in Japan on June 28, 2011. In 40 games in Japan he hit only.202.
He signed a minor league contract with the Los Angeles Dodgers on January 4, 2012. After failing to win a spot on the Dodgers opening day roster, he was assigned to the AAA Albuquerque Isotopes. He played in 133 games for the Isotopes, with a.322 average with 13 homers and 71 RBI.
