i'm pretty sure the college listed is just completely random when a player is generated the only way i can think of to make P5 schools show up more for players worth a 1st round pick would be to set the generator so that the college would be the last thing picked for a player and then weight each college for each range of players eg. 100-91, 90-81, 80-71 etc... probably much more trouble than its worth to JDB since what college a player went to doesn't matter at all in this game
now if he sets up something to make it more realistic in the ways players interact with one another(eg player/team chemistry affecting how they play on gameday) then i could see it making a difference, for instance if a player joins a team that has a few other players that played for the same college (especially if under the same coach in college) he might be able to adjust faster to working with his new teammates.