The 28-year-old signed with Cleburne prior to the 2020 season, then was selected by the Sioux Falls Canaries in the fourth round of the American Association dispersal draft. He made four appearances as a reliever for the Canaries, allowing three hits and two runs over four innings of work for a Sioux Falls team that ultimately reached the Championship Series.

Gunn put together a remarkable 2019 season with Cleburne, finishing the year 5-0 with a 3.11 ERA in 15 starts. The left-hander established a new American Association record for most starts in a season without taking a loss, surpassing the previous mark set by Laredo’s Jeremy Strawn in 2014 (9-0, ten starts).

Gunn operated as both a starter and a reliever for the Railroaders in 2018, making 22 total appearances including 14 starts. He finished the year 3-8 with a 5.69 ERA, working 87 innings and allowing 100 hits. The southpaw struck out 61 while issuing 41 walks.

Gunn was phenomenal in three collegiate seasons with the Arkansas Razorbacks, posting ERAs of 2.57, 1.21, and 0.74. In 60 career appearances, all out of the bullpen, Gunn was 6-3 with a 1.23 ERA and eight saves.

After his junior season, Gunn was selected by the Boston Red Sox in the 16th round of the 2014 MLB Draft, beginning his professional career that year with the Gulf Coast Red Sox. In 2015, Gunn shuffled between three different levels, climbing as high as High-A Salem for one appearance. He finished the season 0-4 with a 5.98 ERA, and was released by the Red Sox organization.

Gunn latched on with the River City Rascals of the Frontier League in 2016, going 3-1 with a 4.68 ERA, then moved to the Pittsburg Diamonds of the Pacific Association for the 2017 campaign. It was with the Diamonds that Gunn first took on the role of starter, going 5-4 with a 4.41 ERA in 16 appearances and 12 starts.