The Nemesis
Semper Tyrannus
Where do the modifiers come from? I'm working on doing my own data analytics and I'd love to know where you read about the junior-league age curving .
The book Stat Shot by Rob Vollman. There's a whole chapter on evaluating junior/amateur players and prospects (and as a result it only covers ages 15 or 16 to I think 22/23). IIRC the model is based on work by another author that contributed to the book.
It's a good book. Designed to help introduce people who aren't full-on stat heads to the ideas of analytics and new evaluation, but it's still useful for those with some grounding in new wave data and all that.