This is a great idea.
The only drawback will be if say "for instance" you get a HC,Off Coor & Backs Coach all on Run Focused Offence, coupled with big "Road Grading" Linemen,even with a great run stuffing defense,the run game may become completely unstoppable even if you use RUN Key on every run play.
This may be right in real life College/ NFL,but in a simulation,which first and foremost, had got to be fun and enjoyable to play,I`m not sure it will keep GM`s around If you feel you can`t compete unless you play a specific way.
The balance has to be there, meaning you can
win and loose using heavy run,heavy pass or balanced offence.
But like I said earlier,a great idea,meaning it`s not just chasing coaches with big numbers.