THe key for schools like BYU, BSU and others non bcs schools is determining who those late bloomers are. BYU has a built in advantage because of the 2 year missions.
The mission thing is also a great thing for late blooming players. Look at John Beck, he wasn't highly recruited out of high school because he was a late bloomer, he comes home from his misson and he gets recruited by many D1 schools, and goes on to have a great college and now potentially pro career. Without the mission, John Beck most likely would not have been given a chance to play at the D1 level.
Unfortunality, many late bloomers never get a chance. And its only getting worse for late bloomers, since players are getting evaulated at a younger age. Most evalulations now begin when a kid is 15 years old.