So to summarize the "geniuses" in this thread, the Patriots defense needs to be more physical, intimidating, play with more emotion, stop being boy-scouts, be more aggressive, hit harder, and make big plays.
Hold the phones, I'm going to send the Memo to BB right now!!!! How could he have missed these easy fixes, while us geniuses here on this messageboard clearly figured it out.
The Patriots 2008 defensive shortcomings definitely do not have to do with injuries, young players learning the system, some aging players, and a lack of talent in some spots (D.O'neil) due to the aforementioned other items (as well as some possible questioning of last few drafts).
Despite all these shortcomings, the Patriots have as many SB wins as the "Scary" defensives of Pittsburgh and Baltimore combined in the last 10 years.
EDIT:
I will make it perfectly clear. I think it is easy for people to throw out a bunch of adjectives that do not have any meaningful correlation to defensive success while watching Pittsburgh/Baltimore play. Sure you can send the house at the QB and hit the other team hard, but if you have guys like D.O'Neil covering a WR, you're pretty screwed no matter what. What I'm saying it is about talent and players knowing their job. Some players (O'Neil) lack the former while younger ones tend to lack the latter (Guyton, Woods, Wilhite, *sigh* O'Neil,etc).
What kills me is that I think the Defensive really improved by the end of the year once the corners become a little more solid, and I would've loved to see what they could've done in the playoffs. Who is to say they couldn't have had the same success as the Cardinals, whose Defensive I would not take over the Patriots.
That's the thing with the NFL nowadays, you just need to get to the playoffs because after that it truly is a crapshoot. Unfortunately the Patriots missed out this year.