First off the Rivals guys don't know jack - 70% of college recruiters pay no attention to Rivals ratings. They are strictly for fans like us. If they were a good indication of college performance, then Texas would never lose a game.
2nd the most important thing is what the coaches are able to do with the players once they enter the program
3rd check last years NFL draft and see how many were 4 and 5 star recruits. There were plenty of 3 stars in first round