In sports photography you tend to take a burst of images. This means the ball could be removed by copying from a previous frame and not leave a cloned section.
"the "correct answer" is the position of the ball as judged by a panel of experts, rather than the position of the actual ball before it was removed, this is because you cannot gamble on an event that as already happened"
which is the case in this particular competition, you are betting that you and the judge with say the same spot as you guess on the image and not where the actual ball was
So, the judges don't know where it was originally? They have to guess as well, and that becomes the correct answer? That seems like a terrible way to judge the competition.
It's the same as the "guess how many jelly beans are in the jar" contests with a baseball in the middle. Even if you mathematically figured out how many should be in there, you'll still be wrong.
(I actually won a jar of skittles that wasn't loaded by mathematically estimating the number of skittles. I wonder if this counts as a non-computer system that I hacked for the YC funding application.)
There were a lot of "guess the number of X in a jar" type contests when I was in primary school. I think I won nearly every single one, because I was (one of?) the the only one(s) estimating mathematically. It always seemed pretty obvious to me.
Even with a baseball in the middle (assuming you know there's a baseball in the middle), it's not impossible to estimate, and your guess is still going to be better than someone who didn't try.
That's the thing. You're not supposed to know if there's a baseball in there.
I guess going at it from a mathematical point of view (regardless of tricks) will give you an advantage over a kid guessing something like "a million" or almost any other random number.