Pacquiao's jab-jab-straight

That move was s simple, yet it gave him so much success in the early part of his career. Of course, he knew that he had to put more in his arsenal to take his stardom to the next level. But why don't more boxers today use that combo? You make a valid point because the 1,1,2 can be changed up to be the building block for numerous combinations. For example: jab body, jab head, straight head. Jab head, jab body. Straight head. Double jab head, straight body. Jab head, jab body, straight body. After that, you start incorperating hooks on the end. Great for amateurs but pros want to use more angled/power punches on their combinations and not be as predicatable. To answer your question though, Manny got away with his straight left for so long as he is southpaw. There is a reason so many Cubans (viva Fidel) are southpaw, and it's not because a high portion of the population are left handed.

Kelly Pavliks coach would have been proud of that double jab Double the effing jab Kelly!

I would assume it's a technique for those with a short reach. Given Pacquiao's reach, it's amazing how great he was offensively.