The the Saints offensive line has sidelined 4 to 5 starting Saints QBs in the last 4yrs.

You are saying that Brees did all of the work. That's not the case, but do you man.
So, you're saying that Brees' operation was not the main contributing factor in those PFF ratings? I couldn't disagree more. Not only has the pass pro been suspect, but the run game suffered under Kroemer's successors and that is including Roushar. The Saints O-Line woes are less to do with personnel and more to do with coaching and that has been true for well over 5 years.