No, I don't think CBJ cares about Rivals, 247, etc., rankings. For fans, the rankings are helpful in monitoring the relative success of the team's recruiting efforts versus other teams. Moreover, the rankings frequently track coaches' interests in players, including offer lists, and, at times, accurately predict the on field success of players. There are certainly exceptions to these general rules, but they are useful tools nevertheless. Finally, there is frequently correlation between team recruiting rankings and on field results. So, rankings have value but are not completely determinative.
All that said, CBJ, like great coaches, relies on his own evaluations. The article about CBJ relying heavily on the evaluations of the former NFL scout on his staff was eye opening. At the end of the day--as reflected in my original post--I trust CBJ's evaluations over all else, including rankings. I'm sure Abernathy is better than his ranking given CBJ's interest in him. Abernathy's ranking on Rivals, thus, is probably not reflective of his talent level, particularly with his offer list.
By the way, anyone with a 6th grade reading level would've read my original post as an inquiry about the rumors, opinions, etc., about Abernathy's potential since CBJ is obviously pursuing him hard (along with other big time coaches), not a criticism of CBJ pursuing Abernathy because of his relatively paltry ranking by Rivals.
