The loss is a crushing one for Pacquiao. His career has been hurt on a variety of levels thanks to the result and that has to be a major disappointment for the former pound-for-pound great.
Looking at what this loss means for Pacquiao, two things become clear. His pocketbook will be missing out on a nice payday and there will be long-term effects on the way he is viewed in a historic context.
No Mayweather Fight
The quest for boxing's holy grail has come to a screeching halt.
Everyone and their brother have been clamoring for a dream fight between Floyd Mayweather and Pacquiao for years now. Both have been at the center of every pound-for-pound discussion in boxing and the hypothetical clash of styles has had analysts salivating.
Had the two been able to settle their differences, they would have been very wealthy because of it. Okay, they are already wealthy, but the purse for a Mayweather-Pacquiao bout would have been record-setting.
With Pacquiao losing two straight and losing in devastating knockout fashion, the chances of this fight ever happening or meaning as much as it once did plummet to zero.
This may be the most disappointing news as Pacquiao's legacy will always be connected with the "what if?" questions surrounding this scenario.
His Legacy is Damaged
Speaking of legacy, Pacquiao's took a major hit with the loss to Marquez.
It doesn't delete everything that he's ever done in the sport—he'll always have the claim that he's the sports first eight-division champion. His accomplishments speak for themselves.
However, one thing that he's always had going for him was a sense of invincibility. For nearly seven years, Pacquiao was unbeaten and dominated most of his fights.
Even fighters who had come close to unseating him in that time span were turned away because he always found ways to win. His two wins and draw against Marquez were perfect examples of that.
Now that he's been KO'd by his most common rival, that aura of invincibility has been dismantled. He'll always be remembered for that seven-year stretch where he was on top of the boxing world, but two losses in a row near the end of his career will be something that knocks down his overall ranking in terms of boxing history.
At this point in his career, Pacquiao must make a tough decision in regards to his future.
Speculation surrounding his commitment to the sport has been rampant recently, so it would be completely understandable if he were to hang up the gloves for good after this one. He has nothing left to prove and anyone in this sport has the right to retire whenever they see fit.
Given that GMA News reports that Pacquiao is planning to fight again, that's not likely to happen.
Pacquiao: (I will) take a rest. After a few months, back to training and back to fight. #PacMarquez— GMA News (@gmanews) December 9, 2012
What's more likely is that Pacquiao will continue to fight. If he goes down that route, he needs to be very careful in choosing his next opponent.
A fifth bout with Marquez makes the most sense for Pacquiao. He was on his way to winning the fight on the scorecards before getting caught and could do damage control by beating Marquez again in their last encounter.
Other than that, Pacquiao will be taking a huge risk again by fighting anyone else. Three losses in a row to three different fighters would be devastating for his legacy.