if he isn't already the dude is one of the fastest punchers of all time.. and is great technical fighter
I would say he is loitering in the 20-11 bracket. A few more fights against good opposition should see him make the top 10.
Why cant gamboa already be top 10? just because ring doesnt have him there doesnt mean others are clearly that much better now, gamboa is the number 1 guy at 126 has solid wins and is dominating with explosive power, in 1/2 years he might be a clear top 5 p4p imo.
A few more good wins or one big win could get him there. If he moves up all the way to 135 and beats Rios, he's in for sure. Don't forget that his Olympic medal came all the way down at flyweight.