I think the Cohens have commented that Blake-Nelson was the only person involved with that film who actually *had* read The Odyssey (and probably in the original.)

He mentioned this in an interview! They sent him the script with a note about wanting to know what he thought, so Nelson figured they wanted his professional opinion as a classicist and was working himself up to admitting that he was more of a Latinist than a scholar of ancient Greek when instead they asked him to play Delmar. That is now one of the best casting stories I have heard. (And does nothing to dissuade me from thinking that Tim Blake Nelson is awesome.)