Public Options / Signing coaches from other teams
As with NFL you can attempt to hire away coordinators from other teams, but (because of the IRL rule that allows teams to block lateral moves, which we assume they will do, as they do in real life) ONLY to be your headcoach.

Why doesn't this apply to AI controlled teams?

There also seems to be an issue (at least in my game) of teams not re-signing their staff when out of contract. For example In my game the Raiders won the Super Bowl and yet they just let their entire staff leave.