What Fields does is unique because he unbalances the defense. You have to do extra accounting for his ability to run, which doesn't allow you to full cover or full blitz. Guys hesitate, and gap discipline gets blown up because even if you are the right read, and the right assignment in the right spot, he can just destroy guys 1 on 1. I don't know if he ever becomes a great thrower, but it sure will help him that you can't just drop 7 or 8 into coverage, because Fields will just destroy you with his legs. The league is going to have to adjust, but those adjustments will give him more opportunities to throw. He is a whole other problem.