How we picked the 50 greatest fighters

Ranking the 50 greatest fighters in history -- producing any kind of ranking, for that matter, of athletes in any sport -- is like flying a kite during a thunderstorm. It might seem exciting and challenging, but you know it's going to hurt.

If one thing is guaranteed about this ESPN.com listing of the greatest 50 boxers of all time, it's that everyone who reads it will have an opinion -- and not one of those opinions will be that we got it exactly right.

Why are there so many overrated old-timers? Why are there so many unproven contemporary fighters? Why is Oscar De La Hoya ahead of Carlos Monzon? Why is Evander Holyfield behind Larry Holmes? Why is Harry Greb so low? Why is Julio Cesar Chavez so high? Why is Mike Tyson in there at all?

But writing a list like this is a subjective science, and an inexact one. With perhaps one or two exceptions, there are no right or wrong answers.

Although few would question that Sugar Ray Robinson should sit at the very top, or that Muhammad Ali, Henry Armstrong and Joe Louis should be at the head of the chasing pack, cases can be made for and against the positioning, inclusion or omission of a good many others. You want to argue that Tony Canzoneri is ranked too high or that Roy Jones Jr. doesn't belong on the list? Go ahead. Chances are your arguments in favor of your rankings are just as good as my arguments in favor of mine.

This list is not an all-time, mythical pound-for-pound ranking. It is not trying to establish who would beat whom if everyone were all the same weight. After all, Roberto Duran lost two of three to Sugar Ray Leonard, but is ranked six places ahead of him. Sandy Saddler beat Willie Pep in three of four bouts, but is at No. 29, while Pep enjoys the stratospheric ranking of No. 5. Alexis Arguello is on the list; Aaron Pryor, a terrific fighter in his own right who beat Arguello twice, doesn't make it.

The fighters in this list have been assessed on four main criteria:

In-ring performance: A subjective measure and, to some degree, unquantifiable, but an important one. There's more to being considered a great fighter than compiling wins and collecting championship belts. There's also the manner in which the fights are fought and the wins are won -- the skill, the talent, the heart. Muhammad Ali brought a whole new style and panache to heavyweight boxing. Rocky Marciano and Evander Holyfield each defined fighting heart. Roy Jones Jr. and Floyd Mayweather Jr. at times displayed flashes of skill and superiority of a kind rarely seen in a boxing ring. At his peak, Mike Tyson didn't so much knock out his opponents as send them flying across the ring.

Achievements: Blistering power or silky smooth boxing moves aren't enough. Boxing's landscape is littered with fighters whose achievements did not end up matching their skill or talent. Almost all the fighters on this list fought at or near the pinnacle of the sport for years -- most either won multiple world titles or defended one title multiple times. Stanley Ketchel defended his middleweight championship 11 times in a short life that ended at 24. Harry Greb won the middleweight title despite being half blind in one eye, and went on to fight light heavyweights and heavyweights. George Foreman won the heavyweight championship of the world, lost it, retired, came back 10 years later and regained the crown at age 45. Henry Armstrong held world championships at three weights at the same time.

The exceptions all have good reasons for being so. Sam Langford, for example, was denied the opportunity to ever contest a world championship bout. Marcel Cerdan was injured during the first defense of his middleweight title and died in a plane crash before he could win back his crown.

Dominance: A factor that arguably works against those from eras with deeper talent pools, but one which rewards those who stood out from among their peers. Joe Louis was heavyweight champion for 11 years. Robinson suffered just one defeat in his first 123 bouts. Cerdan lost only four times in 110 fights, and each of them was due to disqualification, dodgy judging or injury. Pep allegedly once won a round without throwing a punch.

Mainstream appeal: This is the wild-card element. It's a disadvantage for most modern fighters, who compete in a time when boxing is no longer a mainstream sport, but it also conversely greatly boosts the candidacies of those few contemporary boxers who have achieved crossover recognition. In particular, it substantially elevates De La Hoya and Tyson, two boxers who might otherwise not be as high on this list -- or even on it at all. De La Hoya is perhaps the only active boxer with widespread name recognition outside of boxing circles, and nobody brought a buzz to the sport in recent decades to anything like the degree of Tyson -- who, for better or worse, remains synonymous with modern boxing in the public mind.

This list, then, is not just the 50 greatest fighters of all time. It is the 50 fighters who were the greatest in their time. It is a tribute to the boxers who have gone before, and to those who have strived to reach the standard their predecessors have set.

Fifty different writers will have 50 different lists. At a time when boxing is frequently criticized and condemned to oblivion, there will, hopefully, be enough fresh blood and exciting developments in the sport to render this list irrelevant and to elevate a whole new generation of pugilists into the pantheon of boxing's greatest.

Kieran Mulvaney is a freelance writer based in Washington, D.C. He covers boxing for ESPN.com, Reuters and TigerBoxing.com.