Both these men are past their primes, and I'm not expecting much of a fight but anything can happen. Jones of course is much further removed from his best years than Calzaghe is, and Calzaghe is still undefeated, a genuine world champion, and one of boxing's best p4p fighters. So a win for RJJ will be more substantial for all-time status than a win for Calzaghe. I mean, if Calzaghe wins he'll add some more fame to his name and maybe his other results will be noticed more, but no one will put much stock in "Calzaghe beat the great Roy Jones", since he's fighting a mere shell of RJJ. But if RJJ wins it's one of his best wins, and one of the greatest title re-capturings in history. Where would it push RJJ to in the list of all-time p4p ATGs ?
Top 10-15. :good It would be a spectacular effort to defeat Joe Calzaghe at this stage in his career.
It would boost him up there a bit more. I think it'd take a bit off the "Hopkin's hadn't his his peak/Toney was weight drained" disclaimers that come along with Jones current two best wins.
I would love nothing more in the world to see the legend that is RJJ have 1 last hurrah by beating the overrated ducker Cal-slappy, but it just will not happen. RJJ is in no fit state to be taking a challenge like this on anymore.