Q: Why isn't the film [Tales from Earthsea] directed by Hayao Miyazaki?
Hayao was busy with Howl's Moving Castle when a small team (including Goro) formed by producer Toshio Suzuki began work in October of 2003. Although lacking any animation production experience, Goro led the team and drew the storyboards. Hideaki Anno (Evangelion) and Yasuo Ootsuka (head animator of the Lupin series) were greatly impressed by Goro's drawings.
Suzuki felt confident appointing Goro as director after hearing from Anno and Ootsuka.
http://www.nausicaa.net/miyazaki/earthsea/faq.html#direct
(Context: https://secure.wikimedia.org/wikipedia/en/wiki/Tales_from_Earthsea_%28film%29#Reaction_and_box_office )
More evidence:
Q. What were the reactions after seeing the finished cel?
Suzuki: I think it’s better to tell you other people’s words rather than my own. The famous animator Yasuo Otsuka raved over them, saying “These would be beautiful as a film,” and asked who drew them. So, when I said it was Goro, he was truly surprised, saying that the apple doesn’t fall far from the tree. Also, when I showed it to [Evangelion director] Hideaki Anno, he was astonished, and asked, “Why didn’t he start earlier?” Also, he said, “This is totally a Miyazaki animation.”
Q. And Hayao’s reaction?
I didn’t see it. That’s because Hayao expressed his opinion that “There’s something wrong with Suzuki” regarding the decision to hire Goro as director. He was angry, saying, “There’s no way he can be a director. He can’t draw, and he doesn’t know anything about animation!” So first, I showed him the picture for the posters of Alen and the dragon facing each other. Then, Hayao was quiet. That was because it was a camera angle from the side, which Hayao doesn’t draw. That is the kind of power one drawing can have. Then, I told him clearly, “I recommend him.” He was still dumbfounded for a while, though.
http://www.mutantfrog.com/2006/04/10/interview-with-producer-toshio-suzuki-of-ged-war-journal-suzuki-finally-tells-tells-us-why-goro/