Come on man, Lucas did direct Star Wars, American Graffiti and THX-1138, so he is not an incompetent director.

He had substantial creative support for writing ANH, and the superb acting in that film is largely because of Alec Guiness' seasoned talent, and the other actors improvising for themselves. It's nothing to do with Lucas being a good director. He was bad. Really bad. On all accounts during production, the guy was sorely lacking in the social skills department. "Faster and more intense, CO."

ESB was neither written nor directed by Lucas. Kasdan wrote the script, and Kershner directed. Lucas was on the other side of the globe during most of the production.

And American Graffiti I don't see as being anything to write home about, and THX-1138 I've only watched clips of (didn't interest me). That's preferance, though. I'm trying to bring around the idea that the more control Lucas has over a Star Wars film, the more it's panned by critics and fans.