What you describe just doesn't happen very often. I posted earlier in this thread or another thread, but it is very uncommon for P5 coaches to change conferences.
- In the Big12 only Self (from Illinois), Huggins (K-State) and Dixon (Pitt)
- In the Big10 only Underwood (from Okie State) and Turgeon (Texas A&M)
- In the ACC only Roy Williams (from Kansas), Bennett (Wash St)
- In the SEC Cuonzo Martin (Cal), Frank Martin (K-State).
- In the Pac 12 - None
So there are only 9 current Power 5 head coaches who moved between Power 5 schools. And 3 of those guys: Huggins, Dixon and Williams went to their Alma Mater.
Other P5 coaches like Bruce Weber, Rick Barnes and Tom Crean were all fired by a P5 program and hired by a new P5 school. There are other guys who had gap periods like: Ben Howland and Bruce Pearl.
I just don't see ISU hiring a
successful coach at another P5 school
unless ISU is willing to pay a lot more than the coach is currently making. Your $1.2M isn't going to get it done as a lot of coaches already make more than Prohm.
The reality is ISU can hire a P5 assistant, a non-P5 head coach or former P5 head coach.