There are plenty of stories that prove it's not a perfect system. But from a macro perspective, it's actually often more accurate than NFL draft projections, though there are correlations between the 2 a lot of times. A lot of Coug fans don't want to accept that stars matter because so many of our stars on the field were unsung in recruiting. That speaks more to the coaching and the environment than to the individual players' rating.
At BYU, they don't cater much to higher rated recruits, which in my opinion is one of the more significant reasons higher rated players don't have the highest rate of on-field success at BYU. The 5-star guys coming out of high school are almost always taught from a young age that they are better and more deserving of special treatment, and schools that do that for them are more likely to get that players best potential out of them. At BYU, these kids are expected to adhere to rules, work hard, and plan for a potential future that doesn't involve pro football. Highly rated recruits aren't going to be too hip with that.