Looks to me like ACC boys were a bit overrated with how Clemson and ND were no shows in the playoffs. "Special" pickers put them in, ACC was bad. Here are Massey ratings of conferences (put multi part conferences separate) with ratings:
Sec West .794
Big Ten East .765
Big Ten West .756
Big 12 .752
Sec East .753
PAC 12 North .708
PAC 12 South .704
ACC Atlantic .683
ACC Coastal .675 Doesn't include ND, would raise to about .700
AAC .638
Seems like Clemson and ND were in conferences/sections closer to AAC than just about anyone not the PAC 12. Not sure this rating suggest two teams from ACC would be in top 4, and the play seems to confirm that. The games were less competitive than the scores suggest, both winners just wanted to finish out the games after getting big leads.
Clemson had the 54th best SOS and ND 46th, that's after the playoff loses.