Fascinating article--although I don't think that the main hypothesis is all that illuminating. Younger talent excels and reaches the T5 / T10 level more often because those early entrants tend to be the top flight players with immense potential. They don't all actualize said potential, but a guy who is universally recognized as a top draft prospect is going to have more talent / potential / skill all things being equal than a 22 year old coming into the draft at the end of their college career. If the latter group had that talent / potential, then they probably wouldn't have stayed in college [or overseas] for that long. And by no means does that not imply that those players can't round into form as NBA contributors, or even starters. But again, the main thesis of the article was in identifying players with star potential.
Alsacs, I don't think anyone will argue that the top teams selecting at the end of the draft are not in a position [except in the case of extreme outliers] to land stars. Therefore, what separates the wheat from the chaff is the ability to identify role players who can make the roster and contribute. The Spurs excel at this. Other top teams take a different approach, and value free agency far more than the draft.