Im pretty good at playing basketball against some friends in my neighborhood but i suck at real games.?

When I go against older grown ups in my neighborhood( I'm 4'11" and I'm 11 years old) I am a real good play maker and shooter. I kill them with my crossover when I do attempt to. They are very good players. I ask them why they didn't go to the nba and they said they were terrible back then. I don't get it how one of them shoots like kobe and another one is almost as good as ray allen from 3 pt range and the other can get to the rim good. I'm good against them but when it comes to playing in a real game I suck. Am I just bad at playing with 10 people on the court or am I a choker like LeBron LAMES.