I like that idea, and the thing that I think would really help would with zone coverage is that when a receiver enters that players zone they need to follow that player through their zone not just go to that zone and then read and react to the pass. This way zone could be beat but the Qb would have to be patient till the holes developed or a zone cleared, thus also solving pass rush problems. If you have a good zone defense you dline has more time to get to the qb, or if your dline is really good your zone defense doesn't have to be highly rated.