Thank you for this. As the parent of a 2019 RHP, this is very interesting information to me as he starts his recruiting journey. One thing I'd love to know is- (and I'm not sure there would be any data to show this) is there really some type of inverse relationship between velo and ACT/GPA for admittance at a given school, and what that spread might be for a more selective school.
There is a definite inverse relationship for 90% of D1 schools, however the "range" of that relationship at any given school depends on various factors. I don't think there is a direct correlation (1 ACT point for each MPH above 90) as there are some basic minimums to be eligible Let's say you are throwing 95 mph with command - a large Power 5 school might admit you assuming you are NCAA eligible (pretty low standards). I think in football the relationship is greater - sort of like 1 GPA for each recruiting star. Once you get that 5 star, folks don't seem to really care.
As you move up the academic scale, I would say there is still an inverse relationship however it does not move the needle as much - maybe move a kid from wait list (throwing 83 mph) to acceptance (throwing 89) but you still have to have some decent grades to begin with.