2018 begs to differ. We got up to 12th without beating anyone. At the time our best W was unranked NC State (6-3 at that point). We lost at unranked Pitt (6-4 at that point). We played OOC at WMU (6-5 at that point), Wagner (3-7 at that point), UConn (1-9 at that point).
That season proves we can get into the playoff hunt without a strong OOC or even strong ACC schedule. Had we played an easier team than ND and won, we would have finished as high as 10th, at worst 13th. Instead we finished 20th in the CFP rankings.
Had we finished 13th would our OOC have been the cause? Yes, but we wouldn't have been 13th in the first place with a strong OOC schedule.