Potential can be the most damning word in all of professional sports. If someone says you have it, then obviously you have not yet fulfilled it, and if you lack it, well, you might as well start looking for another line of work. Potential has been known to give second, third and fourth chances and create unreasonable expectations. In reality, we never truly know if someone has maximized his or her potential; that answer resides within the individual.However, there are plenty of instances in which we can speculate. Bo Jackson was one of the greatest athletes the world has ever seen, and nobody can deny that he accomplished plenty as a professional football and baseball player. Still, what if Jackson’s career had not been cut short due to injury? Or what if he had chosen to focus his energies entirely on one sport? Not even Bo knows for sure, but those certainly are a couple of tantalizing “What ifs?”Mixed martial arts has also had its share of fighters, who, for various reasons, never reached the heights we hoped they would. This does not mean they were not accomplished, because each of the following did great things for at least a short period of time. However, they, like the aforementioned Jackson, left us yearning for just a little more.As selected by a panel of Sherdog.com staff, here is our Top 10 “Might Have Beens.” It is a list brimming with potential: