[4] Thomas spent his first professional season with the Arizona League Diamondbacks and Missoula Osprey,[5] batting .333 with two home runs, 27 RBIs, and 12 stolen bases in 56 games between the two teams.

[10] Over 114 games between the two teams, Thomas slashed .300/.379/.450 with ten home runs, 55 RBIs, and 15 stolen bases.

[20] In Game 4 of the 2023 National League Championship Series, Thomas hit a pinch-hit, game-tying two-run home run in the eighth inning to help propel the Diamondbacks to a 6–5 victory.

[22] Thomas was named to the 2017 U-18 All-World Team after recording a .361 batting average en route to a gold medal.

[23] Thomas' father Allen was the longtime strength and conditioning coach of the Chicago White Sox.