NC was 7-0, but they had played all of their games except one at home. They beat Georgetown and Ohio State (by 3) in Chapel Hill. They trounced some teams.
Tennessee, after losing their opening game against Chattanooga, has done pretty well on the road and at home. Knoxville seems to be a tough place for the ACC to play.
I don't remember NC beating many really good teams in pre-season. They tend to have good records, but don't really seem to be consistently good. They can upset some good ACC teams. But, they have been a notch below really good the past few years.