If he was going to retire, it seems likely he would have called it a career a month or so after his December loss to Juan Manuel Marquez.
While some observers thought Pacquiao should retire after losing a controversial decision to Timothy Bradley and then getting knocked out by Marquez in the fourth fight between the two men, Pacquiao has not called it a career.
Pacquiao, 34, ran into Marquez's best punch in the final seconds of the sixth round. The punch caught him perfectly on the chin and Pacquiao was out before he hit the canvas.
However, Pacquiao was getting the best of Marquez before that punch. He had been knocked down earlier in the fight, but Pacquiao came back with his own knockdown.
He was beating Marquez on the scorecards and he dominated the sixth round before walking into that punch.
A fifth fight between the two men would obviously benefit Pacquiao because it would give him a chance to bounce back and regain his status in the boxing community, but what could it do for Marquez? How would a fifth fight benefit the 39-year-old Mexican fighter?
On the surface, Marquez has no reason to get in the ring with Pacquiao for a fifth time. Marquez had an 0-2-1 record in the first three fights. Marquez felt that he could have been given the decision in any of the three fights, but those fights had been taken away from him by the judges.
Marquez wanted to stop Pacquiao to remove the matter from the judges' hands. He got what he wanted.
However, Marquez may have as much or more to gain from a fifth fight than Pacquiao.
Marquez had his best effort against Pacquiao, but he was behind until he landed the big punch. Pacquiao made the cardinal mistake in boxing and stopped protecting himself at the wrong moment. He was wading in, looking for his opportunity. Instead, he left himself wide open and Marquez took advantage. So, while Marquez was at his best, he came out on top because of a mistake by Pacquiao.
A fifth fight against Pacquiao would give him another opportunity to show his dominance in the series.
The other issue was that Marquez seemed stronger and more powerful in the Pacquiao fight than he had been at any point in his career. Marquez joined forces with trainer Angel Hernandez to improve his conditioning, and that was a very questionable move.
Hernandez had been a government witness against Olympic coach Trevor Graham. Operating under the name Angel Heredia, Hernandez had previously been linked to drug trafficking and money laundering (source: Boxingscene.com).
That Marquez would choose to join forces with Hernandez despite his checkered past is poor judgement by the fighter, at the very least. Marquez has maintained that he did not know of Hernandez's association with steroids until news reports brought them to light (source: ABS-CBNNews.com).
Fighting Pacquiao for a fifth time while being subject to frequent and unannounced drug tests would be a way to remove doubt from his legacy.
Both fighters need this fight badly. Pacquiao needs it for redemption and Marquez needs it for validation.
In the end, Pacquiao probably needs it a bit more because he does not want to leave boxing with two losses at the tail end of his career.
But the fight would also be good for Marquez.