Any coach is going to come in a pretty tell Dunbar, "That? Yeah, keep doing that," so I'm not worried about it.
While others might think the opposite, I believe it actually works better if a guy like Quinn is brought in because his experience as a DL coach and work with a fundamentally hybrid defense like Seattle's would give him better insight into meshing the systems together. I could see Dunbar's influence over the players making a new DC uncomfortable in terms of his authority without an HC to calm it all down.