Gamboa should be on the list and Broner should be higher.
Gamboa been dropped ALOT, esp in early rounds by a ton of diff guys. Weak Defence + bad chin in early rounds leads to KD's, once he gets going with defense he rarely gets dropped.
Broner just has a weak chin, what he does have is quick recovery rate, something that Amir Khan wishes he had, getting Broner down is no problem, its finishing him off. Gotta time it perfectly, knocking him down with under 30sec to go is useless since he'll most likely survive, but getting him early/mid round is much much better aslong as you can apply pressure.