A static overall is not needed for the CPU, IF the AI is taught how to evaluate skills by position.
Would also allow for variation by team, what they favor, etc.
Basically, imo, your ideas are doing away with a static overall rating and having the AI look at player skills and their team philosophy.
You don't need an OVR for that. You just need the skill ratings and tell the AI how to make their own "value rating" for each player.
You could take OVR out of the game and still teach the AI to do that.
Trades could then take these value ratings into account. FAs could create their own value ratings to determine the contracts they ask for. One WR might look at his SPD and think he's all that (even if his AWR and CTH are average at best), etc.