One of the cornerstones of BB's coaching philosophy is complimentary football. He probably doesn't give his coaches (coordinators or assistants) "full control" in the true sense that they are free to go off on their own and do whatever the want without an understanding of, or consideration for a bigger picture (game plan, organizational structure, team culture, etc.) which is ultimately rubber-stamped by BB. For example, Scars has to be in lockstep with the Josh McDaniels' offensive game plan since the O-line is a subset of the offense. Scars crew needs to also be on the same page as Ivan Fears and the RB's group, QB coach, etc...
That being said, BB has said that while he was an assistant, he enjoyed and greatly appreciated having some degree of freedom so he is probably not a control-freak type of manager. It probably comes down to trust. With Scars tenure and track record as the O-line coach, BB probably gives him more freedom that any of his assistants simply because the trust is so high there.