Before graduating, it was discovered that he needed Tommy John surgery, which caused him to fall in the Major League Baseball draft.

[1] He was selected by the Boston Red Sox in the 13th round of the 2013 Major League Baseball draft, but did not sign and chose to attend Vanderbilt University.

After sitting out the 2014 season recovering from surgery, Sheffield made 6 starts and 16 relief appearances for Vanderbilt in 2015.

[6] Sheffield made one start for the rookie-class Arizona League Dodgers and seven for the Class-A Great Lakes Loons.

[7] He was promoted to the Rancho Cucamonga Quakes of the California League at the end of the season, where he made four starts and one relief appearance and was 0–2 with an 8.00 ERA.

[15] On April 2, 2021, Sheffield made his MLB debut in relief against the Los Angeles Dodgers, pitching a scoreless 9th inning.