Last season, Thomasson played for the Burlington Royals in the Appalachian League. In 47 games, he hit .246 with nine home runs and 24 RBI. He averaged a homer every 18.6 at-bats. He also smacked 12 doubles and two triples.
The ninth round selection of Kansas City in the 2014 MLB draft, the Florida native began his career with Idaho Falls in the Pioneer League hitting .236 with two homers and driving in 27.
Thomasson gained his reputation as a slugger in two seasons at Tennessee Tech University. As a senior for the Golden Eagles in 2014 he led the team with 20 doubles, 22 home runs and 76 RBI. He helped lead the team to the Ohio Valley Conference championship game and was named an OVC First Team performer and a National Collegiate Baseball Writers Association All-American. That season he also led NCAA Division I in RBI and was second in home runs.
As a junior he was also a First Team All-OVC member when he hit .275 with 12 homers and 52 RBI.