Charles was still strong at 32 when he challenged Marciano, in fact he was fresh off 2 electrifying KO's over Satterfield and Wallace,Charles put up a game effort but I dont think anyone thought it was a close fight or that Charles won, the rematch was a horrific beating for Charles . It could be argued that Charles had better heavyweight days and although I personally love his 3 fight Wallace,Satterfeild,Marciano triple, he may have been a better heavyweight when he fought Louis but not so sure...either way the best Charles could do against Marciano would be what he did in the 15 rounder in fight 1, a hair closer or a little less wiser and younger but either way he was still fighting Marciano, who was a greater fighter who always found a way to win.
Charles of 1949 would give rocky A LOT of trouble, but in the end Marciano would prevail. Valentino gave charles huge fits with his crowding tactics, and charles was a bit more aggressive/reckless in his younger days. He would mark up Rocky's face and outbox him for good periods, but I think Marciano's pressure, punching power, and finishing ability would eventually get to Charles and stop him late.