I do agree with some of the sentiments in your post.
CB is especially troublesome, given that it looks like a scheme change - reverting to a style we've seen (and won with before) but do not particularly enjoy (especially being bad at getting off the field on 3rd down) is the team's plan of action. It's just hard in the NFL to get high multiple high performance secondary players while not making major sacrifices elsewhere.
However, much of the rest of what you've said I would consider under the label of "year to year roster churn." I think you over-rate the "misses" on guys like Johnson, Harvin or Bush. If they were potentially crucial additions, they would have been given offers that reflect that the Patrtiots felt that way. Perhaps there were some guys out there who were closer to an A+ rating that the Patriots didn't get due to a lack of clarity with the McCourty and Revis situations, but we can really only speculate there.
I admit that losing Wilfork sucks - but it's fan attachment that drives me to say that. I might still be convinced to try and sign guys like Bruschi, Harrison, Vrabel, Law, McGinest, etc... but that's probably a sign I'm not in a good place to run a team like the Patriots.
I mentioned at the start that I agreed with your sentiments because I had a similar thought earlier today - geez it sucks to see this team come apart a bit. It sucks to have some uncertainty about how the defense will shape up and perform, especially with no obvious place to turn for alternatives (like last year when Revis replaced Talib). But then I talked myself off the ledge, because it's March. Because the team will evolve a lot in training camp. Because the first few weeks of the season count, but don't necessarily define who the team will be for the remainder of the year. All that jazz helps me remember that the sex appeal of March signings often creates false hopes and artificially high expectations.
