The other way to ask it...
Assume for a moment that Darryl Drake is actually the best WR coach in NFL history. If this were the case, how would things be different?
Aside from maybe Bradley again, I don't see who the Bears could have possibly gotten better performances out of. Hester maybe, but as the previous poster noted, he's not a WR anyway, yet he's been moderately effective at the position at times.