During the coronavirus-shortened 2019-20 season, Thomas appeared in eight games for the Detroit Pistons and in two contests for the G League Grand Rapids Drive. The 6-foot-3 guard made his NBA season on Nov. 4 with a brief appearance during a loss at Washington. Two nights later, Thomas scored one point in less than four minutes of run in a home win over the Knicks. A right foot injury than forced Thomas to miss most of November through February. Once healthy, Thomas appeared in two games for the Drive on Feb. 21 and 23. With Grand Rapids, he played 44 total minutes and recorded 34 points, eight rebounds, eight threes, three assists, two steals and one block. Tazz then returned to the Pistons on Feb. 25 and scored three points during a road loss at Denver. Thomas appeared in six of Detroit's last seven games before the Mar. 12 sports stoppage. Over eight NBA games, he averaged 2.1 points, 0.6 threes, 0.4 steals, and 0.4 assists across 7.6 minutes per game. He also shot 35.7 percent from behind the arc. Per 36 minutes, he averaged 10.0 points, 3.0 threes, 1.8 assists and 1.8 steals. On Mar. 11, Thomas played a season-high 14 minutes and posted four points (1-3 FG, 1-3 3Pt, 1-2 FT), one assist and one steal during a loss at Philadelphia.

Thomas spent his rookie season between the Detroit Pistons and their G League affiliate, the Grand Rapids Drive. He played 26 games with the Pistons and averaged 2.3 points on 32 percent shooting. Thomas also hit 10 three-pointers on 29 percent shooting from long range during the season and went 7-of-11 from the free-throw line. He handled the ball well by only registering four turnovers through the year. Thomas scored a season-high 13 points on 3-of-6 shooting -- including 2-of-2 from long range and 5-of-7 from the foul line -- in 20 minutes of action on Jan. 1 on the road versus the Bucks. The five free throws and seven free-throw attempts in this outing both marked season-highs. The Creighton product scored eight points in a Jan. 10 loss to the Kings. Thomas played in 10 games for the Drive, averaging 20.3 points and 1.7 steals per G League contest. The shooting guard appeared in three playoffs games for the Pistons, with his best performance coming in Game 1 of the first round when he tallied nine points on 4-of-6 shooting. Detroit would lose to the Bucks in the first round of the playoffs.