Reposting: Why Manny won:
From Bro Jong Saberola FB account

In a 10-point system, the boxer­ who wins a round is given 10 points, and the other ­boxer gets nine points. (10 -9)
If there was a ­ knockdown in the round (10-8), if 2 knock downs (10-7).

… If a­ judge can’t decide who won the round, it is­ scored 10-10.
Now if u are the challenger, u must be­ the aggressor (Pacquiao vs Cotto) in very close­ rounds the­ Champion gets the 10.

For example if­ Pacquiao would just stay still and Marquez does not­ attack, Pacquiao gets the 10 and Marquez 9.
In this­ case Manny(champion) was always aggressive while­ Marquez(challenger) waits for an attack and­ counters.

Marquez’s body language fooled a lot of­ people. Making people feel that he was the winner or­ at least it was a draw. It may look like he was­ landing more punches but the tricky part here is he­ was on the defensive, luring pacquiao into his ­ tactical traps (remember the challenger must be the one­ who is aggressive to be awarded 10 ).

So even if ­ Marquez did connect more punches he gets only 9 for ­ being defensive and Manny gets the 10 for being the ­ attacker.
Pacquiao got more “10″s than ­ Marquez. Manny wins.