A d-line simply cannot dominate on its own. Anyone that saw the Seahawks-Packers game on September 24 saw that the reason the Hawks got 8 sacks in the first half was that the safeties and corners were in very tight coverage all game long. Rodgers had to take extra looks and he paid for it.
Against Tennessee, our d-backs were in some kind of loose, Rod-Marinelli-5 yard cushion-defense. That might work if you can tackle, but as was evidenced by the play of Coleman and Lacey, they can't. The same happened against SF in that final drive where Smith kept throwing short underneath stuff to Crabtree (which is what we wanted) and our DB's and LB's kept missing tackles (what we did not want) allowing Crabtree to gets YAC's and first downs.
Basically you can rip on the d-line all you want, but any good work they produce is completely dependent on what happens behind them. So far what we have seen is that our d-backs are horrible in coverage and tackling. That is a toxic combo for any defense, regardless of the quality of the pass rush.