SuperFly 2's action-filled bouts ready to exceed all expectations

Srisaket Sor Rungvisai defends his junior bantamweight against Juan Francisco Estrada on Saturday. Chris Carlson/AP

Size does count but not always the way you might think, especially in boxing where bigger is not always better and smaller is frequently as good as it gets.

Saturday's "SuperFly 2" on HBO's Boxing After Dark is a manifestation of this seemingly incongruous reality, a celebration of the sport's lightest and most remarkable fighters.

In the main event, Thailand's Srisaket Sor Rungvisai, the star of "SuperFly 1," defends the WBC junior bantamweight title against Mexico's leading 115-pounder, Juan Francisco "El Gallo" Estrada.

In addition, WBC flyweight titleholder Donnie Nietes takes on challenger Juan Carlos Reveco, and Carlos "Principe" Cuadras faces McWilliam Arroyo in a junior bantamweight non-title bout. Off TV, Brian Viloria and Artem Dalakian will compete for the vacant WBA flyweight title, highlights of which probably will be shown between rounds of the televised fights.

It's probably safe to say that most casual boxing fans have never heard of these guys. They might also suffer from the common misconception that fighters weighing between 105 and 115 pounds just flit around the ring throwing feeble punches. It's an understandable assumption but wrong.

Actually, the opposite is true. Smaller fighters have a physical advantage over their heavier colleagues that allows them to do things larger fighters wouldn't dream of. Biologist/boxing writer Matthew Swain explains why:

"Physiologically, the reason that they can throw so many more punches comes down to surface area to volume ratio in two systems, the skin and the lungs. Small people have a comparatively larger surface area to volume ratio, so the heat being generated by their muscles is dissipated on the skin much more quickly than large people, and because of their much smaller mass and shorter limbs, they are generating less heat to begin with, so they are staying cooler, making them much more efficient.

"Same deal with surface area to volume ratio of the lungs. While a larger person will have a greater volume in their lungs, the surface area within the alveoli (where gas exchange occurs) is not linearly larger also. So they have more oxygen available, which means they are using energy much more efficiently.

"What this means on a practical level is that a smaller fighter requires less energy to throw punches and stay balanced, they get more oxygen, and they stay cooler while working at a much higher volume."

That's the science behind what we will see in the ring Saturday, but there's more to it than that. Perhaps inspired by this natural wellspring of energy, lighter-weight fighters typically have an aggressive streak as large as their bodies are small.

Saturday's card is a throwback in more ways than one. For starters, it's being held at the Forum in Inglewood, California, which opened in 1967 and was the site of many memorable boxing wars, including the celebrated Ruben Olivares-Chucho Castillo trilogy.

It was a golden age for Southern California boxing, an iconic period that lasted well in the 1970s. Mexican and Mexican-American fighters were its heart and soul, and they rendered size inconsequential with machismo in their hearts and menace is their hands.

It was an invigorating change of pace, as different from the standard fare on ABC's Fight Of The Week as sombreros are from fedoras.

The 17,500-seat Forum has been refurbished since then and made a comeback as a boxing venue. Along with Madison Square Garden, it has played a major role in the recent resurgence of boxing's super athletes. But the revival would not have happened if HBO hadn't taken a chance on a flyweight known as "Chocolatito," the nom de guerre of Nicaraguan knockout artist Roman Gonzalez.

Gonzalez's fluid offense was a joy to watch, a relentless onslaught of precise combinations, one barrage after another raining down on his adversaries like cluster bombs. It was breathtaking stuff and by September 2015 he had punched his way to the No. 1 spot in ESPN.com's pound-for-pound ratings.

It all seemed to happen so quickly, but Gonzalez had already fought 40 pro fights before his first HBO appearance in May 2015. He looked virtually unbeatable for the longest time and then suddenly he didn't. Weight-making problems forced him to move up to junior bantamweight, where everything came unraveled against Sor Rungvisai.

Going into their first fight, Sor Rungvisai was a mystery. Sure he had a great record and a ton of knockouts, but the majority of his opponents appeared to be the usual collection of truck drivers and fry cooks fed to Asian prospects. But when he knocked down Gonzalez in the first round with a body shot, it instantly became apparent that the former garbage collector from Si Sa Ket was more than the sum of his parts.

Their first match was a close, toe-to-toe bloodbath, the second a terrifying knockout. Each was awesome in its own way, and although the decision in Sor Rungvisai's favor in the first fight was unpopular, all agreed it had been a magnificent struggle.

There was, however, no disputing Sor Rungvisai's emphatic fourth-round knockout in the rematch. "Chocolatito" was flat on his back, out cold for several minutes before he was revived. It was the perfect rebuttal to those who claim the little guys can't punch.

There will be no easy second defense for Sor Rungvisai (44-4-1, 40 KOs), and that a good thing. Success this far down the scales depends on the sort of sizzling action only fighters their size can provide.

Estrada (36-2, 25 KOs) had been chasing Gonzalez ever since he lost a decision to "Chocolatito" in November 2012. It was intense punch-filled affair that could have gone either way despite the unanimous scores in Gonzalez's favor. The Mexican, who has gone undefeated in 10 subsequent bouts, now gets a crack at Gonzalez's conqueror instead.

Estrada is a better technical boxer than either Gonzalez or Sor Rungvisai. He likes to move and counter but will stand and trade as well. Whether he's still as sharp as when he lost to Gonzalez more than five years ago is the big question. In his most recent fight, Estrada fell behind early and needed a 10th-round knockdown to squeak past fellow Mexican Cuadras by triple scores of 114-113.

Oddly enough, besides Gonzalez, the only world-class boxer Sor Rungvisai has fought is Cuadras, back in 2014, when the Mexican held the WBC super flyweight title.

Cuadras boxed brilliantly, using lateral movement and slashing counters to keep his one-dimensional challenger at bay and build a substantial lead. But Sor Rungvisai never looked discouraged and his persistence finally paid off in the seventh round, when a right to the body had Cuadras doubled over and in serious trouble.

Who knows what might have happened if an accidental clash of heads hadn't brought the fight to a halt in the eighth round? A deep cut over the titleholder's left eye made it impossible for Cuadras to continue, which resulted in a technical decision in his favor.

If Cuadras (36-2-1, 27 KOs) can get past Arroyo (16-3, 14 KOs) in good fashion, which is not a given, he'd could be right back in the title picture.

Filipino Nietes (40-1-4, 22 KOs) is currently the IBF flyweight titleholder and has also held the WBO strawweight and light flyweight titles. Overall, he is 16-0 in title fights and unbeaten since 2004. Not bad for a man most Americans don't even know.

"There's nothing flashy about Nietes," said Ted Lerner, an American journalist based in the Philippines. "You can just tell that he has few natural gifts as a boxer, it's all hard work in the gym. A combination of being in great shape and being very determined has carried him through many fights where he could have easily faded in the late rounds."

Nietes, 35, will be facing another veteran in Argentina's 34-year-old Reveco (39-3, 19 KOs) who has held both the WBA light flyweight and flyweight titles in the past.

"Reveco is a very fine boxer, who mixes the old-school approach of Mendoza (the birthplace of defensive virtuoso Nicolino Locche) with a more aggressive style," said Carlos Irusta, the doyen of Argentina boxing writers. "He is really a mini fly, so he has not the power in his hands that he did when he was in that division -- and younger, of course. He has great courage and is still capable of facing world-class opposition, but I feel his better days have gone."

Viloria (38-5, 23 KO) who hasn't held a major title since 2012, gets what could very well be his last chance when he clashed with Ukraine's Dalakian (15-0, 11 KOs) for the vacant WBA flyweight belt. The American had enough left to hold Estrada to a split decision in 2013 but at 37 is probably closer to a gatekeeper than a titleholder.

Even so, Dalakian, who will be making his U.S. debut, has never fought anybody as accomplished as Viloria. If "The Hawaiian Punch" has one last great performance in him, now would be the perfect time to go for it.

And when this lot is sorted out, there's a Japanese "Monster" out there waiting for them, super fly Naoya Inoue, who just might be the best of them all. With a little bit of luck the resurgence of the lighter-weight in the United States has only just begun.

Disappointment is part of the price you pay to be a fan of any sport, but boxing is the worst. There are so many random factors to deal with, as soon as you think you've got it figured out, it makes a chump of you all over again.

That said, "SuperFly 2" smells like a winner, a fiesta of the little guys who become giants when the bell rings.