Complex sentence: He joined St George as a lock forward and it was in this position that he became an international rugby league star with his legendary cover defence and ball skills causing him to be acknowledged during his playing career as the best lock forward the world had ever seen.
Split into simpler sentences: He joined St George as a lock forward and it was in this position that he became an international rugby league star. His legendary cover defence and ball skills had him be acknowledged during his playing career as the best lock forward the world had ever seen.