He is the type of quarterback who possesses all the tools to be outstanding. Yet, he always seems to find a way to lose the ball game. That's why he was benched in Baltimore in favor of Trent Dilfer. Dilfer is by far the inferior QB, that's why Dallas passed on him. Dilfer won't necessarily win the ballgame for you, but he won't lose it for you either.
Banks has trouble dealing with pressure in the pocket.
He makes the bad pass, or while scrambling, fumbles the ball. That has been the knock against him his entire career. Having said all of that, I think he can succeed in Dallas under certain conditions. The offensive line and Emmitt Smith are the keys. A strong line will protect Banks and give him time in the pocket to make the right choices.