That's true about age differences being much more significant when they're young. And I remember reading about the disproportionate amount of January and February birthdays in hockey leagues of the 90s/2000s so that other part tracks, too.

We're on the same page about the rest. And (aside from foot coordination) it's not a steady skill increase, it happens in big steps as ideas click for them. The worst player in the team can become the best overnight at that age lol