He is constantly hurt. Previous 4 years he played in 51, 75, 36, and 22 games. He has only played in 31 this year and is currently hurt again.
He is in year one of his extension so they might want to move off of that. If you could get the Spurs 1st this year and the Hawks unprotected 1st this year, you could have 3 picks in the top 10. Could be a nice reset for them.