Why Are There No Sports MMO Games?

Brian P. writes "With the online gaming market growing at a remarkable rate and new games being announced frequently, why have developers and publishers shied away from creating an MMO sports game? Online fantasy leagues are bigger than ever and online sports games such as Madden '05 are huge franchises. It seems to me that a logical evolution of this trend would be a gaming experience that lets a player start out as a street-baller and work their way up to virtual super-athlete status. The possibilities are endless...but obviously there's something seriously wrong with the concept because all we keep getting are tiresome sword and sorcery games and online adaptations of megafranchises such as Star Wars."