I understand what you are saying but that "talent" seems to be very hard for science to find. Because in just about every case the people who excel and are regarded as supremely talented have put in more time, way more time, than their peers.
So all you have to do is find someone who did NOT put in the same amount or even less time who ALSO had more success. That would indicate that it's "talent" making up for the lack of training time.
Talent is developed not born. Sure someone may show aptitude for certain things, or may be more physically suited to certain things, no one who is 5'4 is ever going to be the world's best center in the NBA. But people have said that short people can't dunk. A little trip around youtube proves that wrong.
I have often heard the phrase from successful people when they are told that they are very talented, 'if you had worked as hard I have then you would talented too.' Time and again in interviews it comes out that most successful people don't like to hear that their success is attributed to being born with more talent than the next guy. They want you to know that they worked their ass off to get to the point they are at.
If all it took was hard work and practice, then everybody would be playing even.