It really depends of the type of the sports. For example Michal Jordan is Aquarius – an air sign, and his game was lot about exactly that, being in the air and manipulating the ball flying through the air. The other two legendary athletes, Muhammad Ali and Tiger Woods are both earth signs (Capricorns), and the major condition for their success is/was to be firmly with their feet on the ground. Now you would expect Mike Phelps to be a water sign, but he’s not. He is an air sign – Libra, which suggests that he has phenomenal coordination (symmetry) in the water, which may make a significant contribution to his outstanding swimming.
The French psychologist and statistician who devoted his life to the attempt to demonstrate the validity of certain fundamentals of astrology, Michel Gauquelin, wrote that he had found correlations between some planetary positions and certain human traits such as vocations. Gauquelin’s most widely known concept is the Mars effect, which denotes a correlation between the planet Mars occupying certain positions in the sky more often at the birth of eminent sports champions than at the birth of ordinary people. A similar idea is explored by Richard Tarnas in his work Cosmos and Psyche, in which he examines correspondences between planetary alignments and historically significant events and individuals. Since its original publication in 1955, the Mars effect has been the subject of critical studies and skeptical publications which aim to refute it, and of studies in fringe journals used to support or expand the original ideas. Gauquelin’s research has not received mainstream scientific notice.
Athletes usually have a strong Jupiter, 9th house and Sagittarius prominent also. All depends on the sign as that is what will color the Mars energy in this house.
The Gauquelin studies offered a look at tennis players, for example, based not just on the Sun sign, but as well on the rising and other contingencies. Tennis pros, said the Gauquelins, tend to show more Aquarius and Virgo in their charts, for example. The Virgo is usually based on the rising and then the Aquarius picks up the Sun. I’ve never studied it enough to see why this way and not, perhaps, the reverse. I just remember this pattern based, for instance, on John McEnroe who is an Aquarius Sun with a Virgo rising, as I recall. (I know his Sun is Aquarius.)
Hope this lends a bit more to the discussion.