I think Duke's current defensive approach is fundamentally flawed in the era of the new "rules emphases."
Let me explain. I think the system works when it truly disrupts the flow of the opposing team's defense, leading to disorganized offensive sets or steals with easy fast-break layups. When it breaks down, it works when players driving the lane out of control can be stopped by drawing a charge call (makes the possession into a turnover). In the past, when touch fouls on the perimeter were seldom called, and a majority of the out of control drives were called as charges, the defense was very effective.
If the current approach to calling perimeter fouls (i.e., calling lots of meaningless touch fouls outside) and block/charge calls (i.e., the vast majority of the block/charge calls being called as blocks) continues, the Duke defense as it is currently run will continue to be a liability.
It is on the coaching staff to adapt to the way the referees are currently calling the game.
(By the way, if you are going to use the hedge, I think the way Marshall does it is pretty much the best way it can possibly be done. Hedging without really disrupting the flow of the offensive player is a waste of time and nothing but a liability. The weak hedge is at least partially responsible for our loss to Mercer. The pick and roll can be executed very easily when a hedge is attempted but not really committed to.)
"We are not provided with wisdom, we must discover it for ourselves, after a journey through the wilderness which no one else can take for us, an effort which no one can spare us, for our wisdom is the point of view from which we come at last to regard the world." --M. Proust