Add Agents into the mix in GM mode. Some are easy to get deals done with the player. Others are more difficult if they don't like you, or if they like other teams more for their client. (I.e. Rich Paul)
It's be a fun wildcard aspect of being a GM.
On the flip side, let us choose from a section of agents in MyCareer. Better agents get us better offers/ trades/ minutes/ endorsements/ etc