I think the point the poster is making is that JJ and Clay simply prove recruiting is an inexact science, and that argument is bigger and more important than the numbers indicating the percentages of All-Americans that are delivered from the various star rankings.
Of greater importance is that productive players can emerge from across the board, and it's ludicrous for fans to dismiss the potential of a productive player simply because he's a walk-on. J.J. and Clay are indeed lottery ticket examples. But there are examples on plenty of teams - good teams too - of good, productive players starting out as walk ons or low-end star ranking.