There are always going to individuals that are going to be more talented and gifted than others. A genius will always overshadow the person with average IQ who studies a lot, with much less studying required. It is simple capacity that is determined through a lucky genetic combination, nurtured by the environment.
Other than intelligence, you will also have natural skill. In the world of combat, there are individuals that are gifted in this area. These people may have the natural tendency to place their body in their strikes, or have good reaction speeds and naturally light on their feet.