This is just speculation, but does this say anything about Campbell that so many assistants went with the coordinators?
If they stayed in Detroit they’d have a shot at a promotion, plus they also have a great roster to work with, which increases their chance of succeeding and maybe getting a better coaching offer next year or the year after.
So, could it be that Detroits success was more about the coordinators and these assistants know it? Could coaching for Campbell be a bit less of a draw as pundits make it out to be? Or did these coaches simply have connections to the assistants they moved on with?