Pac has been dropped several times in his career including coming from a jab from Nedal Hussein....Lol...but guess how many KD's he suffered after hooking up with Roach?Zero.Nill.Never...The Barrera KD doesn't count since it was a slip though the stupid referee Laurence Cole gave it an 8 count.
So the precedent is there. With better conditioning. balance, defense...yes, a punch resistance can indeed be improved.
Khan for late TKO over Maidana. ;P