Hours after one punch drastically changed the boxing landscape, Bob Arum retired to the showy Nobhill Tavern at the MGM Grand for a late birthday celebration. He turned 81 on Saturday, and he moved among the tables with a vodka and soda in his hand.  “Age doesn’t matter!” he kept saying. “Look at me!”  Arum continued like this, about boxing, about Mitt Romney, about a fight as savage and thrilling and conclusive as they come. The winner, Juan Manuel Marquez had sung “Happy Birthday” to Arum at the post-fight news conference, with a concussion and a broken nose. The loser, Manny Pacquiao, sat in a nearby hospital, having a brain scan.  Someone like Arum, the chairman of Top Rank Boxing, does not survive decades in this sport without an instantaneous ability to adapt. Where some saw a near-certain decline in Pacquiao-related sponsorships and advertising dollars, and where others saw a Marquez victory darkened by drug allegations that Marquez and his camp vociferously denied, Arum saw opportunity. Of course he did.  “What a fight!” he said.  As guests ate strip steaks and lobster claws in cream sauce, Arum’s mind spun forward. Before Saturday, all the Pacquiao-Marquez trilogy had produced was consternation and confusion. Well, that and a lot of money for those involved. The first three fights ended with debatable conclusions, with no clear winner, except for Pacquiao on the scorecards, twice.  This time, Marquez managed to give a definitive answer, a sixth-round knockout that left Pacquiao face down on the canvas, and raise a few dozen or so questions. The first and most obvious concerned those biceps and shoulders and forearms, all so much larger than before.  Marquez climbed into the ring looking less like a boxer and more like a bodybuilder. That in recent years he began to train with Angel Guillermo Heredia, an admitted steroids dealer who testified for the government in the Balco scandal and went by several names, fueled speculation. The difference in size and sculpture was too obvious to ignore. And this at 39.  Pressed repeatedly before the fight, Marquez denied that he had taken performance-enhancing drugs. Marquez has long been an experimental kind of boxer. Early in his career, he drank his own urine during training. In this camp, he received treatments in which cups were suctioned onto his back and arms. But he has never tested positive. Not once. (Heredia did not attend the news conference and was not available to answer questions.)  At the restaurant, Arum considered the turn this narrative had taken. He had expected it, yet he still thought it was unfair. On Friday, he said of Marquez, “Certainly, given the mind-set of the sport, it would tend to taint his victory.” He mentioned a recent two-part report on maxboxing.com that examined performance-enhancing drug use in boxing in light of a series of recent positive tests and the way such tests were conducted, or not conducted.  Arum acknowledged problems with the landscape; with outdated, flawed testing procedures, especially for smaller fights; with no national commission to set policy; and with varied policies among the state commissions. To lump Marquez into the P.E.D. discussion, without proof, Arum said “would be patently unfair.”  Instead, Arum steered the discussion toward Romney, the former Massachusetts governor who visited Pacquiao before the fight and told him: “I ran for president. I lost.” By late Saturday, Pacquiao had lost too.  Arum said Romney told him Saturday was among the best nights of his life. Given recent events, that was reasonable to believe. Pacquiao’s trainer, Freddie Roach, found himself in a difficult position. On one hand, Marquez hit Pacquiao with that same right hand in the three previous meetings, and yet he never knocked him down. In the fourth bout, his punches packed more power, from weight lifting, or training, or whatever. Regardless, that was clear. But to say so would seem like an excuse.  “He definitely punched harder,” Roach said when pressed. “Most people that age go the other way. Maybe he has a secret weapon. I’m not sure.”  Perhaps the politician provided that instead. Mitt Romney: The Cooler. So there was that.  A waiter handed Arum another vodka and soda. “What a fight!” he said again.  He had planned to put Pacquiao in with Brandon Rios next, under the assumption Pacquiao would win. That fight now seems dangerous in light of what happened. Still, a Marquez victory opened up so many possibilities; one that Arum championed — seriously — was a fifth fight.  “I’ll call it Pacquiao-Marquez 5: Epic,” Arum said, as his face lighted up.  Some of that will depend on how Pacquiao recovers, no easy task after a blow like the one he received Saturday. His entourage gathered outside his dressing room after the fight ended, without a dry eye in the bunch.  Pacquiao left the room quickly, his eyes glazed over, and security ushered him up a flight of stairs and away from the cameras that waited down the hall. He continued to bounce, in that way that boxers do, up and down, on the balls of his feet. He smiled, as if to reassure the assembled, but it looked forced.  “Keep your head up, Manny,” someone shouted.  At the news conference, the veteran matchmaker Bruce Trampler of Top Rank tried to make sense of what had happened. He watched Pacquiao train nine times in person before the latest bout. The Pacquiao he saw looked like the Pacquiao of old, the same way he looked at times in the ring Saturday.  “We’ve all seen guys get clocked,” Trampler said. “But that was pretty devastating. I’m still speechless.”  Back at dinner, Arum continued to hold court. He received word from Pacquiao’s camp that his CT scan had been negative for neurological damage, that the champion-turned-knockout-  victim had retired to his suite. He nodded. The wheels spun. So many possibilities.  There sat the promoter, 81 now, on the kind of night that keeps him young.  “What a fight!” Arum said again.
The fourth fight between Juan Manuel Marquez and Manny Pacquiao provided the first clear outcome but still raised no shortage of questions.