A good article on CBS Sports as to why the recruiting sites get it right. In the 2nd half of the article the a discussion turns to team rankings. Here is a key quote:
"Here, I only allowed for one exception: Alabama, which has claimed the No. 1 recruiting class in the nation in Rivals' estimation four of the last five years. As a result, the Crimson Tide's numbers are so far ahead of the rest of the pack in that span that they effectively constitute a class of their own. Of course, the corresponding results on the field make the Tide the single most compelling example of the rankings' success as a tool for predicting outcomes. At the same time, though, Bama has so vastly outperformed even its most well-heeled peers in those rankings that it would be frankly misleading to group them under the same heading. So for our purposes, in this case, Alabama stands alone."