Actually I posted a number of analyses arguing the defense would likely perform poorly. In particular, I felt that the Gilmore addition would disrupt the chemistry. The kinds of missed coverages we saw against the Chiefs is a symptom of this poor chemistry.
In the history of the NFL, many, many teams have bet the team on some high-priced free agent with a long-term contract. When that free agent didn't pan out, the team could do poorly for a decade. A team could do more poorly than one would expect from the wasted cost alone. That's because of the affect on chemistry. Everyone on that defense knows, for example, that Malcolm Butler did everything he was asked and more (much more) for the last three years. And everyone knows he's getting paid a guaranteed salary of about 5% or so of Gilmore's. There is no inspiring speech that Patricia or Belichick can deliver that is likely to overturn this kind of arithmetic in the minds of the players.
I said before the season that I was profoundly pessimistic for this season. At this point, not only am I profoundly pessimistic for the season, but I could see the Gilmore situation affecting the next several years as well. And the fact that we lost the most brilliant and original non-QB offensive player of the decade (cue the chorus of Edelman-criticism) is the icing on the cake here.
When I watched the Patriots lose to the Chiefs, I constantly heard the announcers boast about the 40 times of our players. They've never done that, and it's about as bad a sign as one can have. We've become the team that boasts about 40 times while missing coverages. I saw this happening all throughout the preseason with the media and "fans" on here obsessing about combine scores of players: only losing teams do that actually.