I think when looking at this you need to determine which players are the most independent. I.e. you can have a horrible running back behind an amazing oline and he can be all pro. Although I think oline and dline are very important especially a left tackle the lines are veyr much units so one guy cannot make an o or dline which eliminates them. Although kickers and punters are very independent they don't count because they are not real football players. No matter how good WR's are they need a qb so they're gone. This leaves me with LB's CB's, safeties and QB's. I think a weak LB can be hidden a lot easier than weak defensive backs because they can burnt on huge plays.Although safeties are very important it's a very deep position because a lot of guys can play it(undersized backers, oversized corners) This means my top two positions are qb because he pretty much controls everything and CB. This is because corners are often in man and it is a one on one matchup where if they fail or succeed it is completely dependent on how well they play. I think the big difference between these two and the other positions is that you cannot have huge holes at cb and or qb and win superbowls.