Badoer sucks because it's a new track, and he hasn't had much time in the car. While he is a test driver, test ban has kept him out. Also when you haven't raced in 10 years, and never been that good either, it's obvious you will loose your pace and all finer skills you need.
And of course, because he just isn't any good. I'd say Ferrari was really nice letting him drive as a reward for his efforts as test driver.