If Kessler could compete with Calzaghe for 6, and land punches, what do you think a younger Calzaghe would do to him? Prime Calzaghe wins, old Calzaghe's opinion doesn't matter much.
:nono :nono :nono :nono :nono Physical prime Calzaghe (8-9 years ago) would have lost to Kessler. The Calzaghe from 5 years ago would have only beaten him in a very close fight.