Lebron showed perhaps his greatest weakness in this series. When he's not getting the superstar calls he's used to, he shuts down. I honestly don't think Lebron has the skills to be a great champion (yet), nevermind to be called "the best ever." What he has is strength, speed, and athleticism. He is a very inconsistent shooter (from anywhere, including free throws) and has NO post game at all. His success comes from his "bull in a china shop" strategy which relies on pure strength and speed to penetrate and finish at the rim, but when the calls don't go his way he seems to lose confidence in that technique. Compound that with a poor shooting night and all of a sudden he's scoring next to nothing in the 4th quarter.
What he does have going for him, aside from pure athletic prowess (which I admit is extremely important), is fantastic defense, great passing, the best fast break in the league (although that comes from his athleticism), and the occasional hot shooting night. These skills alone are enough to make him one of the best in the league, but he needs to shore a lot of things before he becomes legendary. As it stands, despite being bigger and stronger than Wade, he is MUCH more easily shut down.