I recently saw the some of the movie/art installation The Clock. What it does is point out the primacy of the editor to cinema. The editor can create almost anything out of the raw material that the director produces. Check out the posts marked mashup in this blog. These may only be "amateur" creations but show how editing can completely change everything. Editing and editors matter more in film than is immediately apparent.
There is not a day/year goes by when I do not curse George Lucas to the heavens for what he did to Howard the Duck. It was confusing that a director like Lucas could be so sensitive to his interpretation of golden age pulp sci-fi could be so ham handed when adapting a comic book. At this point the most profitable part of Hollywood is comic book adaption. But it must done right, by fans who understand and respect the material. Admittedly Howard the Duck was the first movie adaption for a long time however it be safe to say that just about everything that George Lucas has done since the last real Star Wars movie, The Return of the Jedi, sucks.
And why does everything that George Lucas has done since 1983 suck? The short answer is that he divorced his wife and film editor Marcia Lucas. Without her he was lost. Read at this long exploration of Marcia Lucas' influence on Star Wars, Tribute to Marcia Lucas at the Secret History of Star Wars.