One of the most underrated things Roy has done with this team is instill a holistic approach to defense. Everyone plays defense. Wingers come back into position if the defender is chasing someone, centers pick up their man but not only their man, they also roam in their zone.
Offensively, he's got guys in defensive position already in key passing lanes around the neutral zone, like where O'Reilly was last night. We play a really nice 1-3-1 in the neutral zone and a really good collapsing 1-2-2 defensively.
I love the technicality to his coaching, it shows intelligence which our team has lacked for years.