Two things:
They're not a solid, or even adequate defensive unit. They're still bad. Dojji says "young", but that's counting your chickens before they hatch. At the moment, the defense is bad, and that's being very generous, they're one of the worst units in the NFL.
They're flawed, but they're not getting better yet. Getting better means they've turned the corner for good, if next year they're somewhere in the middle of the pack defensively, once again I'll admit they were young, and undeveloped. Right now, they're just not very good. I'm not one to evaluate based on potentials.
Finally, they have absolutely not reverted to their 2001-2004 philosophy. They're offensive minded. They move the ball well. Why do you think BB keeps going for it on 4th downs? In fact, I believe YH213 (I'm not ragging on him, for once, he was the only person who originally expected the Patriots to be better without Moss) said that it was because BB trusts his offense more than his defense these days. You can revert to an old philosophy if you're doing the exact opposite as the previous philosophy, it doesn't make sense.