Timing has a lot to do with how power punches feel to the other fighter. DLH did a great job of getting inside Mayorga's wide punches and catching him with his own straighter ones. Remember that the punch that knocked Mayorga down in the 1st round was a left hook thrown while Mayorga was throwing his own.

The same thing happened to Vargas in his fight with Tito. They both threw left hooks, but Tito's got there first.

Finally, I think there's also something to the theory that a fighter loses the ability to shake off head shots very well after absorbing a devastating KO loss. This, I believe, affected both Vargas and Mayorga as a result of their fights with Tito and well before their subsequent fights with DLH.