What are signs to look out for?
But the best way that I've come across is to judge character traits. Intelligent people always have listening as a core component, where as less intelligent people will be very dismissive and constantly interrupt people. These are traits you can definitely sift out in interviews.
So a great coder will have different characteristics than a great manager of coders. The most obvious difference is probably that one has no potential for leading until they at least acknowledge the possibility of empathy being maybe a little bit important. If they aren't open to that, then they're in the "coder" category by default.
So, in that "coder" category, building on your sports analogy, technical experts first shake out unfairly based on natural talent and what resources (human, material, etc) they happen to have. After that it's all about hard work and creativity. If they coast on their random starting stats they go into the "won't be a great coder" category by default.