the reality is none of us has a clue about the oline depth because we haven't seen them play too much, but that seems to equate to a weakness to most people.
If you don't understand why you don't plug in random dudes in the line because, for instance, flo is hurting then you don't understand the dynamics of good o-line play. Chemistry is the name of the game on the line and the guys have to think as one unit, you have to know what the guys around you are going to do, and when you are down a man or two you don't just blow it up completely, plugging in guys just to do it.