Hehe, it guessed Jeff Gordon for me, but I thought of Dale Earnhardt Jr., so I win.
It guessed Boris Becker right, but I just picked him over Michael Stich to make it easy.
So, in conclusion: As long as you think of the most obvious character in a certain field, it will probably guess somewhat correct. Which is good enough for the simple-minded who can't come up with anything not obvious anyways.
btw: On a third game it guessed some apparantly czech guy who I have never heard of. Which is not too far off considering that I forgot whom I actually thought of that time.