The problem is to pay him the minimum like a 3rd string back. If he wants more, he can be replaced with a 4th or 5th round pick.
He is not a starter and will never be a good starter.
A 3rd stringer has to be very unique specialist to command any more than the minimum salary. I don't see him as a #2 guy because if he is a 20 carry a game type of guy, you are not winning the game.
A great guy on your team, but do not commit much salary or assets to retain him where you forfeit the opportunity to use those assets for other pieces on the 11 other offensive guys out on the field more often.