We have a very good idea of what he is capable of. Let's put it this way, he was totally outplayed by a noodle-armed journeyman backup, the same QB that set an NFL record the previous year for the lowest yards per attempt in the modern NFL. Fitzpatrick was playing behind the same beat up "line", with the same "weapons", in the same knuckle-walking dumb offense. In a word: pathetic.
Clinging to the fantasy that Edwards can and will suddenly, and because of external factors no less, invest himself in the game and become a top-10 QB is simple self-delusion.