You are correct if you are on age and playing well you are in a great spot. But you can not argue with the fact that the top kids going to the top schools are private school kids who are 12 months to 18 months older then a "on age" kid. Its like saying you do not have to be really tall to play in the NBA look at Spud Webb!
So I do not need stats to say a older player is getting D1 roster spots over on age kids more times then not.