For those of us who like to debate the Platonic ideal of what is sport, boxing creates the second biggest conundrum after golf (which everyone seems to want to define out). Last weekend's fight between Manny Pacquiao and Tim Bradley, in which Bradley won a split decision that has been universally derided as wrong to the point of being corrupt (the promoter of the fight has called on the Nevada Attorney General to investigate), brings the issue back up.
One of the four elements to my preferred definition of sport is objective scoring. This means points are awarded and winners determined based on objective criteria, rather than through "judging," which involves inherently subjective and usually undefined (and undefinable) criteria such as "artistic merit" or "whichever fighter you would not have wanted to be in a given round" (an oft-accepted standard for judging in boxing). One way to distinguish this is to ask whether the judge could explain his conclusion in a way likely to convince anyone who watched the fight and initially reached a different conclusion.
So what of boxing? Fights obviously can and often do end by knockout, the ultimate objective determination. But, as here, they often end on a decision by judges who exercise completely unchecked decision applying a standard that, quite literally, has no determinative criteria beyond "which guy won?". This contrasts with amateur boxing, in which judges look to who landed the most punches, an objective standard (although of course subject to manipulation and error). We could tweak the definition to include boxing by defining this element as "objective scoring, or at least the possibility of determining a winner by something other than subjective judging." So the possibility that a fight could be decided objectively is enough, even if some fights are decided via subjective judging. But it is hard to call something a sport (as opposed to a contest or competition or exhibition) after a fight like this one, in which you have the feeling that things were decided by people who were just making things up, but you could not, in fact, explain why.