Hideaki Anno is a well-known animator and director. He is not, however, a well-known voice actor. Prior to 2013, he appears to have a total of two voice-acting credits to his name - a minor character in FLCL and a minor character in Abenobashi Mahou Shoutengai. There's nothing terribly surprising about either of those - both were created by Gainax while he worked there; I'm sure nobody objected to letting their ace director have some fun in the recording studio.
Then, for some reason, Anno was cast as the adult voice of Jirou Horikoshi, the protagonist of Miyazaki's The Wind Rises. Why?
I know that Miyazaki has never been a fan of hiring from the usual stable of anime voice actors, but you'd think he'd at least want somebody who had some experience in the field...