We didn't give the OL a chance last night IMO. We totally gave up on multiple formations, we ran the same damn play on almost every run we tried and ND figured out they didn't have to worry about anyone getting behind the LBs. The simple filled the gaps and there weren't enough guys to block everyone.
I don't think what we saw was due to poor line play. I think it was due to cutting the playbook down to about 10 plays and somehow expecting ND to be fooled. Nix was way too conservative.