When a guy just jumps up in weight, I don't think it's good," he said. "It takes a little while to adjust. A good example is Bernard Hopkins. He put his weight on the right way and took his time.
Despite his disastrous title challenge against Roy Jones in 1995, Pazienza did well for himself at the higher weight, fighting at 168 for 10 years, losing some, winning more, and making some good paydays along the way. The difference between lightweight and super middle? A solid 33 pounds.
"You have to remember there weren't too many guys like Vinny, as far as strength is concerned," Duva said. "There was nobody like him. He was in the gym all day lifting weights and getting bigger and stronger."
If strength is the primary factor, how does one account for the success of former heavyweight titleholder Chris Byrd, who was the physically weaker man in just about every heavyweight fight he had?
After losing in the quarter finals of the 1988 Olympic Trials at junior welterweight, Byrd won silver at the 1992 Games in Barcelona - as a middleweight. He turned pro at 169 pounds in 1993, decided to jump to heavyweight three fights later and (at just 6'1" and never more than 215) beat such top-rated behemoths as Vitali Klitschko (244), David Tua (233) and Jameel McCline (270). He also drew with Andrew Golota (238). Each was much stronger than Byrd.
Byrd's remarkable success notwithstanding, much of the concern about Pacquiao comes not just from the size difference that will be on display December 6, but also the weight swings evident in the fighters' histories.
De La Hoya turned pro at junior lightweight and has fought as high as 160. Pacquiao turned pro at a tiny 108 pounds and as recently as last year fought just below the junior lightweight limit of 130. He won a piece of the lightweight (135-pound limit) title just this year, against David Diaz. How can a guy who hasn't gotten any taller be as effective at 147 as he was at, say, 120?
"It depends on the individual and his physical composition," said veteran trainer Roger Bloodworth. "In this fight it depends on what weight Pacquiao walks around at. He may not be as quick at the higher weight, or he might not punch as hard."
Bloodworth told HBO.com that how a fighter puts on weight - and how long it takes him - is critical.
"When a guy just jumps up in weight, I don't think it's good," he said. "It takes a little while to adjust. A good example is Bernard Hopkins. He put his weight on the right way and took his time."
Guillermo Jones is the poster boy for taking the slow route and making it work. Jones twice challenged one-time WBA junior middleweight belt holder Laurent Boudouani in the late 1990s. After the second fight, a split-decision loss in Las Vegas, Jones jumped to super middleweight. And then light heavyweight. And he kept going.
Today, Jones is the WBA cruiserweight (limit 200 pounds) belt holder. The difference between junior middle and cruiserweight? Try 46 pounds: Seven more than the 39 pounds Pacquiao will have gained between turning pro in 1995 stepping into the ring December 6 at the 147-pound limit.
James Toney took a similar route. A rail-thin middleweight champion in the early 1990s, Toney stopped in every division on his way up to becoming an admittedly pudgy heavyweight. But few can deny how good he was, winning the IBF cruiserweight title against Vasiliy Jirov in 2003 weighing 190 pounds, 30 more than he weighed when he stopped Michael Nunn for the middleweight belt 13 years earlier.
Toney's arch nemesis, Roy Jones, turned pro at 157 pounds in 1989 and weighed 193 the night he beat John Ruiz for the WBA heavyweight title in 2003. That translates to 36-pound weight gain over 14 years, but about 20 of it was for Ruiz, who had a 33-pound weight advantage on fight night.
Certainly that's comparable to Pacquiao's 39-pound weight gain over 13 years and 15-pound deficit on fight night.
"Ruiz is a big guy, and my life is on the line," Jones said in typically melodramatic fashion, before completely outclassing Ruiz over 12 one-sided rounds.
The best barometer of all might be De La Hoya's last bout, against Steve Forbes, a largely passive and mostly under-powered fighter who once won a title at junior lightweight. De La Hoya over-powered him through the distance, but Forbes still landed enough to crack De La Hoya's cheekbone.
Certainly, De La Hoya's size will give him an advantage on December 6. But if history is correct, being bigger isn't going to be enough - not against a buzzsaw like Pacquiao. De La Hoya's going to have to be a better fighter, too.