Wtf are you talking about? He is clearly Top 2-3, right after Beckman. Go read Brannew's dialog
"His executives have EACH won
their own fame, and his crew boasts a
high average bounty." At best Usopp is going to become a better marksman in terms of accuracy (as shown in Dressrosa).
People forget Usopp doesn't even have basic armament yet, and he can't even use observation properly.