James Harden has done a pretty good job fighting LeBron James for post position and making his shots difficult on defense. He is doing an incredibly horrible job with basic tasks like passing the ball to open teammates.
I think these two things are related. Guarding James is tough, even in the fourth quarter. He’s so physical, and he’s become much better at moving without the ball. For a smaller guard like Harden, that takes a physical toll, and that physical fatigue has led to mental fatigue offensively.