David Epstein

Range takes the ten thousand hours story and asks where it does not apply, which turns out to be almost everywhere outside chess and golf.

Epstein separates kind learning environments, where the rules hold still and feedback arrives at once, from wicked ones where neither is true. Early specialisation pays only in the first sort. Roger Federer played several sports late into adolescence and that is the book's opening.

The Sports Gene came earlier and is more contested. He was an investigative reporter at Sports Illustrated, and the sourcing habits carried over.