Because I didn't see what the judges saw: him connecting as many punches as Marquez across the entire 12 rounds. I understand that the challenger has to impress, I've seen enough boxing matches to know that if both fighters perform equally, or even if the challenger is only marginally better, the belt stays with the champ. I don't have any confusion in my regarding the soundness of that logic.
However, in that fight, Marquez wasn't just marginally better. It was a counter-punching class act on the part of Marquez, go read what some of the boxers are saying. Go watch the match a second time, then a third. Then come have this conversation again. The compustats, by the way, are a headache and are sometimes misleading. Moreover, what Trowbridge saw to make him award his score, only he knows.
Like I said though, feel free to believe what you want. I've seen Pacquaio fight brilliantly and less so. In this last fight he was neither. In this last fight he was borderline mediocre. But that's just my opinion. What is less subjective are the look in his eyes after the fight, and Freddie roach's words. Marquez was right to walk away, I say this because I would have done the same. Besides I find it a little odd that a fighter walks away after a title fight... That's another first.
Well, Ringside can say what they want. It's all part of the hype of the sport; the true pound for pound was not in that ring. The true pound for pound won against Marquez. Decisively. And that was despite the additional vitamins from urine drinking...
Of course this is all, in my opinion.