it's interesting how a person's natural strengths lead to certain competencies becoming well developed to the point that other important competencies develop at a much lesser rate or even can be stunted in their development by comparison.

You see this play out in the case of mobile QB's who are gifted runners. When they feel pressure, their coping mechanism is to fall back on their well developed competency for dealing with the stress, run. When they first drop back to pass they have their eyes downfield and the ball up poised and ready to throw. When they feel pressure in the pocket and start to run however the ball comes down from a throwing position to a running position and their eyes stop looking over the entire field as they now shift some of their focus to what's directly in front of them.

I think that polarity (well developed/less developed competencies) is a barrier that inhibits a QB's development and mastery of the passing game as they trade off potential big plays throwing the ball for the hope of a big run. imo however the opportunity for the big play is greater if the QB keeps his eyes downfield determined to throw than if he diverts his eyes down to focus on defenders in front of him.

In this area I think Romney has an edge over either ZW or Hall. Romney's style of play at QB reminds me of Ty Detmer. Romney certainly isn't as physically gifted as either ZW or Hall but he showed his gifts were all upstairs.