When given his usual offensive line impeccable protection Brady is extremely accurate and efficient pocket passer. When he is under pressure, as yesterday, Brady is rather ordinary, unable to scramble to extend the play, he folds on contact.
Roethlisberger has had to work with a sub-par offensive line for most of his career. He often takes a beating in games. Not as accurate a pure passer as Brady, Roethlisberger is more of a football player who happens to throw passes. Shaking off would-be tacklers and extending plays is his forte. Really, I'm not sure Ben could be as good as Brady if he had equal protection, but it's quite obvious that Brady is not as good as Ben when he doesn't have the protection.
Roethlisberger, IMO, is somewhat under rated generally, in part because he does not have the classic QB style like Tom, Peyton, Drew, and Phillip who many consider better than Ben.
Have you seen PR run?