I'm guessing they're the ones no one likes flying with. In JFK I only ever flew with one CA (only 2 legs thank goodness) that I didn't want to ever fly with again, who was also a JFK guy, at the time anyway. The CVG folks I got the chance to fly with were great, but I do understand that more of the 5%ers hail from there. All in the whole 13 months or whatever it was I was flying...