Honestly, what is an OC? What are the qualifications? Is it the play caller? Is it the author of a team's offensive scheme? Is it the guy who makes personel decisions?
to me, it may or may not be all of those things, but as long as you have coaches who know their jobs, and do them well, then why do you need anyone to be known as the "OC"? I think that in the current environment of football (College and Pro), this is something that you're seeing more often.
In UL's case, Hudson is the OL coach, and probably has a fair amount to say about the running game and the passing game, wrt play design and so forth. Munoz will be doing the play calling, and will be in charge of developing the passing game. And overall, it's Bustle's scheme and he probably oversees everything anyway.
Maybe I'm wrong, maybe I looking at it to simplified. Maybe we do need a guy that is an OC that oversees everything. Maybe Bustle being too involved with the O, and not involved enough with the D, is what has hampered this team.