When Sonny Bill Williams placed his Rugby World Cup winner's medal around the neck of 14-year-old Charlie Line after the final, the cross-code star completed one of the more remarkable image transformations in sport.

Along with his undeniable ability on the field, Williams' selfless acts captured the hearts of the world during the global showcase.

Indeed, in the days since the All Blacks' 34-17 triumph over Australia, arguably only legendary duo Richie McCaw and Dan Carter have received more adulation than the Kiwi super sub.

It is a far cry from the vitriol directed his way following his infamous walk-out on the Bulldogs in the NRL. Or the criticism over his last-minute U-turn to play for the Kiwis at the Rugby League World Cup. Or any of the reactions to one of his many switches between union and league, where Williams is often accused of being all about himself.