Better ratings matter and so does having a playbook to fit you players. A bit simple.
If one had to align coaches styles to receive some sort of benefit perhaps these contracts would not be so easy. And building a complete staff would be way harder when obtaining ratings aND some sort of cohesion between styles .
I would think perhaps a compatibility of each type would be the way to go if this was implemented, like a coach specific stat. There are a lot of coaches who can run various types of defenses or offenses beyond their primary type. Perhaps add the stats and then each play's bonus be based on style familiarity.