How is it a "paradox"? It makes total sense that kids older and bigger will dominate most sports. It will re-enforce their self esteem and confidence and help them get even better. I don't dispute the phenomenon, I've never heard it called a "paradox".

I think what was meant here is the Relative Age Effect: https://en.wikipedia.org/wiki/Relative_age_effect

Many here probably recall if from Super Freakonomics.

Ah, "effect", of course. This is what I meant

Well, I made a mistake by saying that "NHL players most likely to be born in December" when in fact they most likely to be born in January. December is the horrible month to be born for a future NHL star (https://www.quanthockey.com/nhl/birth-month-totals/nhl-playe...). So it is not that obvious, isn't it? :)

Sufficiently unintuitive reality is indistinguishable from paradox.