I don't mean to say that talent doesn't matter: things such as intelligence matter more than Adams gives them credit for

I think the relative contribution of intelligence vs. practice varies substantially depending on the nature of the particular task. A key problem is to identify tasks as intelligence-dominated (the smart guy always wins) vs. practice-dominated (the experienced guy always wins).

As a first observation about this problem, notice that clearly definable or objective tasks (chess, pool, basketball) tend to be practice-dominated, whereas more ambiguous tasks (leadership, writing, rationality) tend to be intelligence-dominated.