What makes a defense great? Is it having a recognizable MLB like Brian Urlacher? Is it having the fiercest pass rusher in the league? Is it having the most punishing defensive backs like New Orleans?
I would argue that none of those make a great defense, but they are all pieces of the puzzle. I think that the only consistently true way to judge a defense is based on how many points they allow on a weakly basis.
Jared Allen was statistically the league's best pass rusher, but his defense allowed the second worst (28.1) points per game. The aforementioned Saints and Bears have certain parts of their defenses that are memorable and well publicized, but both still allowed just over 21 points a game.
With that said, where did the less publicized Tennessee Titans defense rank? Allowing just 19.8 points per game, the Titans were the league's eighth best defense in the league in that category. Some may contest that the AFC South isn't a division build with explosive offenses citing the Jaguars and Colts offensive woes. However, in 2011 the Titans played the Saints, Steelers, Panthers, Falcons, and the Texans twice. None of those teams are offensive pushovers.
Also consider that the Titans are ended up playing four rookie starters on the defensive side of the ball making them the youngest defense in the league. It is fair to assume that those talented defenders will only get better next year. In fact some of them clearly got better as the year progressed.
For instance, Karl Klug struggled to anchor against the run early in 2011. However, by the time we played Houston the second time, I thought he was one of the better players against the run in that game.
While the defense was expected to struggle after losing Stephen Tulloch and Jason Babin, I think that it is safe to say that the Titans far exceeded expectations. The future is promising, and if you want more proof look no further than Matt Miller's B/R 1000 project. He ranks all the starters in the NFL and then some. On the list of defensive tackles, Klug and Jurrell Casey place 13th and 15th respectively.
If that wasn't enough praise on the young defensive unit, another rookie has reached similar heights. Rookie MLB and fan favorite Colin McCarthy ranks 17th after only starting a few games in his rookie season. With the inside of the Tennessee defense set up so nicely for the next few years, and the addition of a strong edge rusher in Wimbley, the Titans could crack the top five defenses next year.