I wonder how DeVoe would take it if he realized the truth. When he mockingly said, "Right, ROOKIE?" to Barry, and then laughed, he was the one who knocked Barry off-balance emotionally. He derailed HIS OWN plan. And he did so by indulging in an emotion: arrogance. He had said that Harry had been undone by his own hubris, and then DeVoe became a walking illustration of exactly that.