I think there are two divergent views here related to nature (mythical slow processor in the brain) and nurture (coaching that builds on strengths). I'm not sure that there is much in the way of nurture ability in the NFL. I know Brady sung the praise of Weiss, but Weiss was never able to translate that anywhere else, although that could be due to sloth. And we haven't seen a lot of mid-round QBs succeed in the NFL. The nature argument is probably mostly horsefeathers too. The NFL has a way of sussing that out well before the draft.
I think a team has to be very careful to draft a QB that works with whatever scheme the team is using based on the HC/OC. It's not nature or nurture, it's compatibility. In the case of the Bears, when have they had the stability to do that?