Many stroke victims can potentially restore most, if not all, function of affected limbs through a method called constraint-induced movement therapy.
Many of these stroke victims have brain lesions, some massive, in the areas that control their movement; these victims have brain damage yet they can learn to move again! Most athletes don't have brain damage... so why can't athletes learn to move well... VERY well?
There should be no reason "healthy" athletes can't drastically improve movement control and mobility to unforeseen levels, when many stroke victims can restore much of the motor control of their limbs, minus certain parts of their brain.