OU in 2005 was minimized a bit by the way the rest of their season turned out, though I disagree with OU fans that they were terrible that year. They just lost to some pretty good teams. 2013 LSU was OK, but they weren't worldbeaters either. I honestly don't remember Clemson being that big of a deal. Good win on the road against a quality opponent, but they were just coming off the Tommy Bowden era of good-but-not-great.
If Ohio State holds serve the way that everyone expects them to (win or lose this game), then the only comparisons would be OU in 2008 and Nebraska in 2001, teams that ended up playing for the national title.