Prohm came in when Nader and Long were Seniors, Thomas and Monte were established Juniors. I don't know how anyone could feel Prohm made them good players, or even developed them. Thomas got better his last two years, but I'm still not sold that wasn't just him maturing as a player.
Morris PER his soph year, was 21.4. He went to 20.4 as a Junior then 24.7 as a Senior. Morris was good before Prohm ever got there.
Nader went from 12.2 to 15.8. His biggest improvement was after leaving ISU it seemed, and not under Prohm.
Nader's numbers jumped significantly his one year under Prohm. His shooting percentages and metrics grew a lot the one year under Prohm and got him drafted.
Thomas was a train wreck under Hoiberg, he was hardly an established player. His sophomore year, he didnt start a game and only averaged 15 MPG.