Patricia was operating as a special assistant to Belichick last season. There was speculation that he was taking the "Ernie Adams role", but presumably he was involved in a lot of aspects of the team, not just defense. And lower level coaches moving among offense, defense and (especially) special teams is not unheard of.
Not excusing the situation. But among explanations, I find the one that is based around Belichick feeling that both Patricia and Judge, who certainly could be expected to have a working familiarity with the key concepts of the offensive system that the team has deployed over the years, were a better choice than trying to find someone outside the organization. The evidence continues to build that the decision was a mistake, but I find that explanation more likely and more satisfying than just chalking it up to "hubris and arrogance" or utter incompetence.
The Andy Reid example is instructive in a way: after firing Reid, the Eagles went through 3 more coaches, 3 playoff DNQs, and 4 seasons without a single playoff win before hitting lightning in a bottle and walking away with a Lombardi. And the Eagles haven't won a playoff game since earning that trophy, although it seems likely that will change this year.