An interesting article from TheRinger. It compares the inexact science of how HS players are ranked and actually turn out through college and to the next level.
I think as Michigan fans the example most used is Mike Hart. Other notables in the past were Michael Crabtree. In this article you'll notice that Nick Fairley was #27 ranked OG on Scout and NR per rivals. Prince Amukamara is another one that stands out also. However you will notice a lot of the top prospects were highly ranked coming out of HS too.
An interesting read.