I agree, Triano was terrible, he had to go. Casey was great last year though, I'll admit, because they needed a fresh voice and the constant reminders on defense because it was so abysmal under Triano and a new defensive culture had to be established.
But now it's a year later. He's established what he wants from his team. He doesn't need to constantly bark at them anymore during the game, it's time to have confidence in your players and let them execute what you've been preaching during practice. I think Casey's Assistant Coach background is playing into that, head coaches have more of a feel for when to just let the players play and save the lessons for practice and the locker room.
Calderon, Bargnani, De Rozan, Amir Johnson, Kyle Lowry are all veterans now, they don't need to be coached from the sideline when playing defense during a game, it's ridiculous. And if I were them I'd feel a bit humiliated as a professional athlete that my coach thinks I need reminders about where to be and what to do during an NBA game.