Luka needs the pain of defeat, kind of like Booker did. People keep blaming the talent around him, but I think that is partly Luka's fault. I fully believe CP3 could make this a very competitive series if he and Luka switched places. It's not that CP3 is better overall, he is not, it's that Chris knows how to get his team involved. They would all be scoring and that would engage them defensively. They also would not have the gaping hole defensively that Luka is.
Luka is far from his ceiling. He is a smart player and very, very, young. He will improve his body, and I believe he is going to learn how to involve his teammates more and dominate the ball less. He will learn how to get his teammates involved early and then dominate the 4th quarter--he is probably learning that from CP3 right now. Motivation and competitiveness is a factor--but I think that will improve as he comes under criticism. Up until now basketball has been easy for him.