It has been pointed out to you before that this defense stat is misleading. Our offense shortens games (rushing burns more clock and TOP reduces number of opponent drives). If you click the yards per play stat, you'll see we were 64th.
I know you pointed that out before, that's why I threw out there the idea of the O keeping the ball for 40 minutes a game being more important than points if the D is really incompetent. I could have said it this way, "Using the stat of total defense, the GT D has gotten demonstrably better. From 64th in 2010 to 43rd in 2011 and 2012, the GT D has improved to 28th in 2013."
Our improvement in D occurred with the O only keeping the ball in 2013 for 20 more seconds a game on average than 2102 (33:19 in 13 vice 32:58 in 12). I think the reason our D did better is that we got more stops on third down (we went from 74th in 2012 to 34th in 2013) -- when we didn't get stops we gave up big plays. But I have no problem with that. I'm glad you came back with this, because I hadn't figured out (or forgotten) the reason of our greatly improved total D being our improved 3rd down play.
As you know, the D yards per play allowed has stayed about the same over the last four years -- 69th, 65th, 74th and 64th in 2010 to 2013 respectively. But that doesn't tell the whole story either. No stat tells the whole story by any means. The O and ST count a lot too. No one stat tells the whole story because it is a team game. The O can help out the D a lot by staying on the field and having fewer possessions for the D to play. Or the O can score so many times that the D only has to face a desperate O reduced to only passing. The ST can pin the other team deep or get blocked punts.
The best stat is a team stat because it takes into account the interplay between O, D and ST - if I could only chose one stat, it would be a team stat. I happen to like Power Ranking; others like Win / Loss.
Give me the coach that gives us the highest Power Ranking (or W/L) and I'll like his philosophy.