NBA Cup, the Mavericks lost to the Clippers 127-133 in double overtime.

In this game, Flagg, the top pick of the Mavericks, performed well. He scored two tying goals at the end of the first overtime and at the beginning of the second overtime, but the team still suffered a defeat.

In this campaign, Flagg played 48 minutes, making 8 of 13 shots, 0 of 3 three-pointers, and 0 of 1 free throws. He scored 16 points, 5 rebounds, and 1 steal. He made 4 turnovers and had a plus-minus of -15.