I will say that meditation will improve everything you do and by god it could possibly cure cancer and help you to win championships.
There have been several studies on the place of mental imagery in sports performance. They seem to indicate positive results. For more information see this link it will be a good starting point.
http://www-rohan.sdsu.edu/dept/coach...6/rushall4.htm
In my own experience meditating has helped me to learn concentration, concentration aided my ability to visualize or image movement and performance. Once I have reached a place of feeling like I know the technique then I find it far easier to learn it and perform it with a greater degree of accuracy. I can tell you from experience as well that when I go into the ring if I do not feel like I have already won then I will lose. What the mind imagines is the same as what is "real" to the body. If you disbelieve me then try imagining biting into a slice of lemon.
Meditation quiets the channel and removes static from the mind.
Imagery creates the feeling of the desired outcome.
The feeling then helps the muscles do their job free of stresses over outcome of the activity.