hewitt is much bigger than ferrer. he is about 2 inches taller and 10 pounds heavier.
I think ferrer would have reached a slam final and with a lot of luck maybe even won one in a weaker era but he never would have been a dominant force.
I don't think roddick is a lot better than him. in fact ferrer leads roddick h2h 7-4 and a lot of those matches were in roddicks prime before his prime.