So if you could somehow prove that Viv Richards possessed hand eye coordination that was far in excess of what anyone else measured and thus very few if any people could match that advantage, that would disqualify him? That would certainly be something quite abnormal.
What if someone was born with a mutation in his muscles that allowed for abnormal arm speed. That would mean he is disqualified from being a fast bowler?
Or a sprinter that had like 99% fast twitch fibers in his muscles? He would be a human anomaly (and certainly would cause scientists to study him very closely), and it would certainly be a physical deformity (though you couldn't see it), and it would give him a natural advantage when sprinting (and a disadvantage when doing long distance). That would mean he is disqualified?
So this is a standard bell curve that you can overlay for any ability. Let's say this represents a unique ability such as hand eye coordination.
The vast majority of us would fall in between within 1SD of the mean (meaning 70% of the population is clustered around the middle where the curve is the highest). Between 1SD and 2SD are probably some good athletes fall, like club and some county cricketers. +2SD and above are the natural athletes, and most FC batsman would fall at the top 2% of the population.
The further you go right, the less chance you have of finding other people like you. Most batsmen at the Test level are probably well above 1%. Let's say a genetic freak (like Richards) comes along that is so far right, that he falls like .00000005% of the population. That means there is likely not one other person in the world who was lucky enough to be born with this 'deformity'. At what point in this curve do you say 'This is too much of an advantage?'