Just like some people can't be taught how to shoot, some can't be taught how to play D. It's not just about effort. Few people play with as much effort as Wilbekin does, but he can't play D. He's too slow, not strong enough and too small. He's often in the right position and then gets beat. Or like happened against Duke and other teams, he was simply to small after making the correct rotation.
People here like to bag on Dinos' defense. But if you watch last year versus this year, he is markedly better. However, he still doesn't have great lateral mobility. But he is where he's supposed to be and puts forth great effort.
With all the cheap fouls called against him, JC is a bit hesitant on D. In a couple of blowout games, Danny needs to get Ts bitching about the soft calls JC gets but doesn't receive. He even needs to talk about them in post game interviews.
As opposed to Wilbekin and Dinos who have taken the coaching well, but don't have the talent to be plus defenders, McClinton is just lost. He doesn't get it. He is out of position a large percentage of the time he's in the game. This causes a lot of rotations by other players to cover up for him, and it leads to open shots.
We shouldn't be upset at Arians lack of defensive ability. He does try really hard, but he just isn't good. We got him to score. No matter what level you are on, there are guys who are good scorers but coaches know are mediocre or worse defenders. Everyone isn't a two way player.