Here's the thing:
If you're a company dominating a market, the goal is to keep a continuing philosophical culture. When you're a company like Apple or Amazon, you want to make sure everyone is following established processes that are working. You want to train your own people based on your own business culture. As long as you're on top, the goal is continuing to replicate a winning formula. That worked for the Patriots for many years, developing their own people and promoting internally.
As so often happens, a shift happens in every company that dominates a market. Sometimes it's gradual, and sometimes it's sudden. But the company realizes that it's no longer on the cutting edge of innovation. The philosophies that worked for a long time, no longer seem to work. And even worse, it seems that all of the top people merely echo the same concepts that worked in the past. Everyone merely becomes "a yes man" and tells the leader he's right to go back to those same exact ideas that made them successful, and the problem is always identified as the people or personnel not properly carrying out the code; the leader, having hired and taught these people that same philosophy, doesn't see the blind spots.
This is why bringing in external people at high levels of the organization, and bringing in coordinators and assistants from other teams, is essential for the Patriots. They need to be challenged and adapt. It doesn't mean they need to change everything and that everything they're doing is stupid. I don't think anyone can look at this team and think the coaches are buffoons. But they're clearly not innovative like they used to be. And they're not going to get innovative when all of their coaches were brought up in an environment where you build a team a certain way, coach a certain way, and are unable to think outside the box. This isn't just a gameplan thing...it carries over to the entire culture, personnel decisions, and the draft.