The scariest thing in basketball is a superstar without a weakness in his game. The fact he's a superstar tells you there must be something this person is doing on an elite level. But if there is no weakness in their game, then you are in a "pick your poison" situation. LeBron's last weakness was his jump shot, and then the Spurs helped him with that.
We've normalized the fact that LeBron has been to 9 Finals in his career. Most players didn't go to nine playoff series in theirs. Out of those 9, you could say LeBron beat himself to an extent two times - the first two times. In 2007 against the Spurs and versus the Mavs in 2011. The Mavs were mostly psychological, the first time LeBron was the favorite to win in the Finals, and he wasn't prepared to deal with the pressure.
The Spurs were a different story. First of all, let's take a moment to appreciate this was his second season in the NBA, and the man took his team to the Finals. The Cavs second-best scorer that season was Larry Hughes, with 14.7 points per game. Enough said. But, the Spurs saw a weakness in his game. A vulnerability they exploited that motivated LeBron and helped him become No. 18 on the career 3-pointers list last night. (via Spectrum Sports):
"I just want to be able to not have any weaknesses, you know, and allow a defense to dictate what I do. Because of the Spurs, in a lot of my early years, [they are] part of the reason why my jump shot is a lot better today. My first Finals appearance in '07, they went under on everything and I didn't shoot the ball, I wasn't comfortable with shooting the ball at that point in time in my career. So I give a lot of thanks to their scheme, a lot of thanks to a lot of other teams that I went against."
Greatness in sports comes as a combination of extraordinary talent combined with an ultimate dedication to improve. The thing that makes LeBron so special is that he always finds ways to improve his game. He didn't win every Finals he was in, but he was never beaten the same way. You may point out a weakness in his game once, but rest assured it won't be there next season.