No, it doesn't assume anything, and neither should you. The data is what it is, and the math indicates a strong correlation.
If a talent isn't applied nor developed, it doesn't mean squat. That is my point.
ALL other things being equal, your numbers will work out every time. Otherwise, you don't have a valid experiment.
But all other things are not always equal, and thus, you will find among those ranks people who applied what they had to work with and did better than those who may have had a higher IQ.