There's the tie-ins, but then the bowl can select a team, in this case, from the ACC, that has no more than 2 additional losses, to the team that should make it.

I have read in a number of places that VT was the #3 team, but 3TechFanz makes an interesting observation. Even if NCSU was #3 in the ACC, VT has the better ranking and overall record and they had the option to choose VT over NCSU.

I remember a few years that FSU had a 7-5 team and was selected to a bowl 2 spots above where they should have been. It's all about a bowl maximizing their profitability, within certain perameters.