Lots of reasons for that, though Lebron's play is not one of them. You simply can't ask for any more production from an NBA player pushing 40 years old. What has hurt is when they let LeBron try to play the role of GM. Memo to all current and former NBA superstars - if your name is not Jerry West, stay out of the personnel decision-making, and let those qualified do their jobs. The Lakers simply got beat by a superior opponent again. With LeBron and Davis taking up nearly all the cap space, there is no way to bring in another star. The fact Austin Reaves was able to develop into the third or fourth-best player on the team has made them more competitive...but one can only ask so much from a player who supposedly was not good enough to be drafted (especially defensively).
We see this in all sports, but so few can transition from being a great player to being a great head coach or GM. To my knowledge, the only great NBA player who was also a great head coach was Lenny Wilkins.