You're absolutely wrong. Rankings are highly correlated with college production. Higher rated prospects generally do better than lower rated prospects. Lower ranked players can certainly have better careers than higher ranked players, but that's not generally the case. Thus, I would rather have a a four or five star player than a three star player in almost all circumstances.
Of course, I would rather have a 4/5 star over a 3 star any day of the week, but what I'm trying to convey (not sure I did correctly in my original post) is that just because he isn't 4/5 star doesn't mean he can't be a program changer. That's all.