That's a loaded statement because I would argue success cannot be accurately assessed without a balance of opportunity. If one can demonstrate that many one-and-done HCs are black, that counters impact the success rate. What happened in NE and LV this year is a reflection of that.
Obviously, if you have a losing season, getting fired should not be a surprise. However, black coaches in a first-time HC are rarely in an environment of patience.
You cannot force people to hang out in places they do not hang- out, and the NFL is a reflection of society.
Due to the broader political discussions that are happening in the US , I think that's all I can say on this type of board without wandering into politics and history.