Over the years, many have mentioned him being on the cutting edge of NBA offensive concepts, and he's received nothing but the highest praise from Frank Vogel, Monty Williams, etc.
That said, I do question how much influence he had over the offense in Phoenix. Whenever Vogel was asked about the division of labor on his staff, he said Young was performing the duties of a lead assistant. Never mentioned him having an "offensive coordinator" type role.
BYU will be an opportunity for him to implement his own system after excelling in a supporting role over the past 15 years. Can't wait to see what he comes up with.