I was absolutely shocked to listen to the Scout podcast after the Duke game and have all 3 basically agree that ND has very little defensive talent.
This is example #3,249 of college football being "what did you do for me lately." It's an oversimplification, but it more or less boils down to "If you win, everyone is fine, if you lose everyone sucks."
Now the list you created above, just like the defensive stats for some schools, are certainly skewed by the fact that LSU has to play Alabama every year and that a few other SEC schools always have particularly good defenses. In other words, there offense from 2010 to 2014 would have fared better in the Big 10. And no one in the MAC has to play Florida, Alabama, and Auburn in the same year.
LSU, like us, had a scheme issue. LSU has tons of great players on offense. Their WRs and RBs are usually awesome. Their QBs have been half-ass, but that is partly a result of kids not wanting to play in such a closed offense.
LSU players should be able to cobble together a Top 40 offense every year with the players they have. We should be able to do the same on defense. All our guys are clearly D1 capable, some of them get drafted. Diaco was right: play fundamentals, don't give up big plays; bend don't break is the way to go in college football. Our offense should be winning us more games. We just need to be pretty good on defense.