To be honest, I feel there should be a degree of Warboss.
You've got your standard warboss, the one you see in the games now, he's got himself a proper WAAAGH! going, he's got his own personal Nob squad, maybe a few bigger nobz scattered out and about, with a buncha boyz and bitz.
Then there's the
MC Warboss, the boss that would have Warbosses under him, he's got nobz aplenty in his army, he's got more boyz, a giant Space Hulk just up there sending roks down, he's got a klaw the size of a space marine chapter master. This is the orks "Chapter Master" in other words.
Then you've got things like Thraka, who are just huge, though I kinda wish for an Apocalypse Style "The Beast" Gigantic Creature for orks.