Odds of Becoming an All-American, by Recruiting Ranking
5–Star: 1 in 4.
Top 100: 1 in 6.
4–Star: 1 in 16.
3–Star: 1 in 56.
2–Star: 1 in 127.
All FBS Signees: 1 in 45.
Obviously there are many 4 and 5 star kids that do not end up being great, but odds are much higher that they will be better than a 2 or 3 star player.
http://www.cbssports.com/collegefootball/eye-on-college-football/21641769