Of course he's not ready right now... That was his first NFL start at home (in Primetime no less) against what is likely the best defense in the NFL this season. I think he'll be fine after a season of on the job training... I have no idea what his ceiling is (because of his size limitations) - but I am pretty sure his floor is like Kirk Cousins.
seasons like this for a bad team can break a rookie QB. They knew they didn't have a team that was one ppayer away. Why not let him sit a year and learn? But now days if you draft them high, you must put them in.. Teams should learn from GB.