It's not age, it's style. And a shooting big gives you more room to go for layup. Exactly what LeBron has for his entire career. It's all about getting the team better, not personal stats better. Kobe does the former, LeBron does the latter. And Kobe still gets more double than LeBron, because he works on the post for most of his points, while LeBron starts from the top of key.