The Patriots have two coaches who used to be coaches under Belichick before leaving and returning in Judge and O'Brien. They have six coaches who were members of the organization as players, including Klemm and Jerod Mayo. They have two of Belichick's children on the defensive side of the ball in Brian and Steve Belichick. Six other coaches on the staff have no pro experience outside of working under Belichick. The only exceptions are Will Lawing, who coached under O'Brien at Penn State and with the Texans, and Evan Rothstein, who worked under Patricia with the Lions before following him to New England.
It's not my place to say that any of these coaches aren't qualified, and I'm not suggesting that they aren't suited for their roles. What is accurate, though, is that the Patriots are almost entirely staffed by coaches and players who either had preexisting relationships with Belichick or who had no pro coaching experience before joining the organization.