Quote: Jukesays "Based on your earlier quote you seem to think that it's weight that dictates whether he can become a world class back rower.'"
I know this is probably a bit much for your little brain to comprehend (you might want to ask your physics teacher), RL forward play is about power - speed, strength & weight combined. Farrell is a great club player who might develop into an international player, he has all the qualities apart from size.
What do the following world class players have in common?
A Farrell, Scully, Sam Burgess, Betts, Ellis, Morley?
The only other player I could think of in the L Farrell mould is JJB, another great club player & fringe international but not world class. Andy Platt is the same height as Farrell but developed into one of the best props in the world at well over 16 stones.