I would say those numbers are high. Making it to the pros is a very long shot. We've all been around really talented players and they can't even sniff the talent of the pros. There is one thing to have talent and then there's another thing to have pro talent. Like golf, they can all drive it a mile, but which ones have the talent to hit it close and then hit the putt...not very many! It's not always about physical talent, but mentally you also have to be off the charts.
Prob more like 1/1000 at D1 level and then another 1/100 for pros. Just think of the total athletes at each level and how quickly it shrinks.
I would suspect their is so much tampering going on now with schools actively recruiting from other schools rosters behind the scenes. I would bet Bama is leading the way. They have the morals of mangy rats.