My sister in law has a couple of nieces who went to ISU the last few years and they said Purdy was a party boy. So maybe he got more serious in his prep for the draft thus the improvement??His footwork looked better in the combine and his arm strength actually got bumped up considerably. I don't know what sort of workouts they had him doing, but it made a big difference.
I think I remember Jeff Hornecek in college had a sideways spin on his jump shot and when he got in the NBA he fixed it. Someone asked him why he didn't fix it when Johnny wanted him to and he said Johnny didn't pay him. So maybe similar situations??