Not really sure there was just one reason the concours attendance was so low. The downtown venue for O'fest was not the most car-friendly, and the local chapter was not heavily involved in the event, so that may have played some part. The overall attendance was down from recent years, as well, so that also affected the pool of available cars. I know several large collectors who didn't bring anything this year, as well. As Don mentioned, there is talk of separating the drivers' school/club race from the social side of the event, but I'm not sure which side would get the concours.
Next year O'fest will run in conjunction with the Pittsburgh Vintage Grand Prix, and that, coupled with it being the 50th anniversary of the 2002, should help attendance. Hope to see you all there!