was a little skeptical at first about the genetic argument regarding east asian sprinting, but the fact that there are so few white sprinters that are sub-10 is eye-opening. lemaitre is an exceptional one that sticks out for me. matt boling is relatively far off at 10.15 but is still young. it wouldnt be the most surprising thing to me if he dips under but i know a lot believe he's overrated.
the pull of talent from more popular sports i think can also be telling, but much harder to quantify. baseball, for example, is by far the most popular sport in japan. if you look at the roster of a typical pro bball team in japan, their measurements are pretty comparable to an elite runner that bulks up. hard for me to imagine the average american farmer boy dreaming of, and choosing, running under the hayward lights for a world championship vs hitting dingers for his local AA baseball team, the akron rubberducks. the thought just never crosses their mind, and we may have missed countless potential legends of the sport because of it. but i guess thats the beauty of witnessing those that do end up rising to the top.
i personally believe that for large countries, there is enough genetic diversity in terms of physiological build, even in one as homogenous as japan, to attribute lack of results to losing the youth sports popularity contest for decades, because it takes years/decades to build the interest, culture, and infrastructure to be consistently world-class.