[1] His junior season in 2003 he was 10–1 with 114 strikeouts in 58+1⁄3 innings pitched and also batted .632 with 18 homers and 53 RBI, earning him the Athens Banner-Herald Northeast Georgia Player of the Year honors.

[2] The following season, he ranked 36th in Baseball America's Top 100 Prep Prospects list while having a 6–0 record and 1.25 ERA with 80 strikeouts in 36 innings.

[3] He was selected to the Southeastern Conference All-Freshman team and made school history when he struck out the first eight batters he faced against Winthrop on May 18.

[2] The Bulldogs won the SEC Championship and advanced to the 2008 College World Series, where they finished as the runner-up to Fresno State.

[11] He made his professional debut with the West Tenn Diamond Jaxx of the Southern League on April 9, allowing three runs while retiring only two batters.

[9] He pitched in 31 games with a 2–2 record and 6.48 ERA that season[12] despite being shut down in May for a brief period with a "dead arm" that was attributed to his long layoff between the draft and signing.

[12] On July 1, he was promoted to the Triple-A Tacoma Rainiers of the Pacific Coast League,[15] where he allowed 10 earned runs in 13 innings of work.

[12] On July 31, 2011, Fields was traded to the Boston Red Sox (along with Érik Bédard) in a three-team transaction that sent Trayvon Robinson and Chih-Hsien Chiang to the Mariners, and Tim Federowicz, Stephen Fife and Juan Rodriguez to the Los Angeles Dodgers[16] The Red Sox assigned him to the Portland Sea Dogs of the Eastern League, where he pitched 17+1⁄3 innings in nine games and allowed six earned runs.

[17] He was promoted to the Triple-A Pawtucket Red Sox of the International League on August 5,[18] where he pitched 13+2⁄3 scoreless innings over 10 games.

[20] He recorded his first major league win on July 23 against the Oakland Athletics with one scoreless inning of relief[21] and his first save on August 5 against the Red Sox.

[9] In 2016, he began the season with the Astros but allowed 12 earned runs in 19+1⁄3 innings[1] leading to his demotion to the Fresno Grizzlies of the Pacific Coast League on May 12.

[12] On August 1, 2016, Fields was traded to the Los Angeles Dodgers in exchange for minor league infielder Yordan Alvarez.

[28] Fields struggled with his fastball velocity in spring training in 2017[29] and was optioned to the Triple-A Oklahoma City Dodgers to begin the season.

[1] In Game Two of the 2017 NLDS against the Diamondbacks, he faced two batters in the top of the eighth inning, striking out J. D. Martinez before allowing a double to Daniel Descalso.