you have to also account for the academic differences amongst these institutions. so as to not hurt anyone's feelings, I wont specify amongst the preps, but there are pretty marked differences in the testing levels, acceptance rates and academic reputations and "output" from school to school. there are kids who attend and thrive at some of these schools that would not be admitted academically to other schools on the list. the best example would be to maybe think about the difference between Princeton and Hofstra. great schools, great lacrosse but a Princeton degree will open doors that Hofstra wont.
the same applies to the preps, so coming in to do 2 years (likely after reclassifying) or doing a PG year, can open academic doors for a student athlete that will not open staying home and playing for their local high school regardless of the quality of the program at home. another season, another chance at the SAT or AP classes, another year of lifting and an opportunity to live away from home in a more guided manner all add to the total value and make the adjustment to college much easier.