Offline Owner Mode - Head Coach Dilemma

[Razor Rex]

I'm playing as the Buffalo Bills in Offline Owner Mode.
Not a bad season as I've made the playoffs in my first year.

But the fans hate Doug Marrone. He's only a level 3 coach with next to
no abilities purchased and XP for the coach is coming very slowly.

Do I fire him and hire a level 25 head coach? Will it make a difference?
What about the Scout and the Training staff? Do I need a World Class trainer and a top level scout?