Another way to think about depth is absent injuries, how many guys will rotate into a close game to rest starters and how much drop off is there when they do? Not indicative of certain positions like QB or C where coach prefers continuity.
For me at BB we have 5th year senior Marcus Allen who has looked good when healthy, and Dedrick Mills played a lot in the spring game and looked ready right now (blocking running and catching, college body). Barring injury, both of those guys will play some this fall with MM. So to me we have two guys who can reasonably be expected to fill the void.
Behind that we have Quaide and Besen who we'd have to call bodies, but at least we wouldnt be pulling guys from other positions. So for me personally we have average or middling depth at BB. One can argue Mills is untested and Marcus Allen is injury prone so our depth at BB sucks, and that's reasonable too.