I caught the last round or so of this and what a shame for it to go the way that it did, unfortunate clash of heads. Though I'd missed the first rounds I heard the score card and it did seem that the baby faced assassin is past it now and should concentrate on his out of ring activities. Very sad but it comes to everyone in that game.
Saying that though, knowing the heart of Barrera, the fight, had it not been stopped due to the clash of heads, I expect would have gone to the end. He's a tough little character as he proved in the awesome battles with Morales. Fights that probably shortened both of their careers.
Had it run the distance I am sure that Barrera would have started to bother Khan a lot.