It's also called puberty, what is your point? he had to bulk up because if he was to play first grade the players he would be playing against are bigger, it is part of being a professional footballer and some players struggle with the commitment that it requires.
The backs at the club wouldn't be any heavier than the nrl average and they never start the season at ideal playing weight because they lose it as they become match fit and then are only required to sustain it throughout the season.
you do, but you dont need anywhere near as much endurance as a fullback. fullback is constantly roaming the field. wingers generally walk backwards and forwards with the play, then drop back on fifth if its going their side of the field.
