I see a lot of insecure mexicans in this thread, already cowering in fear, trying to talk themselves into the comforting "Rios would KO Provo" ****, when they KNOW FOR SURE that Rios would take the beating of his life.
You obviously have not seen many of Brandon's fights and he is only called a punching bag by those who know very little about boxing. The only one sided fight Brandon has been in where he took any unanswered punches was against Pacman. Abril never hit him much and Alvarado threw everything he had against Brandon and never hurt him.
With the way promoter negotiations go it is highly unlikely that a boxer actually ducks another boxer. It is more likely a promoter or trainer decides it is not in the boxer's best interest to take the match.