I'm like a one trick pony on this :)  But how many RBs do they need in a game?  The best running games use 2 guys, one for the bulk of carries and one for spelling him.  We saw this last week when there were 2 or 3 mins remaining in first half.  CJ was averaging over 4 ypc and in a very critical 3rd down, McCoy decided to bring Booker in off the bench.  This is nonsensical, and of course it resulted in a punt.  

My theory on this is Elway was so disgusted by the ground game last season that he overloaded.  It makes sense, I guess, especially with CJ's health, but now they're abandoning basic run game principles.  The best rushing offenses use 2 and it's always been that way.  And I've never seen anything to indicate CJ can't be that guy (when healthy).  After him, I'm not sure but Booker has looked really good.