Instability isn't caused by introducing an interim title if a winning culture and systems are already established. There are many examples in the non football world where people leave for a year and return to there jobs such as maternity/paternity leave or mental leave and everything is fine upon return because the company can keep things running smoothly.
I'm sorry, but professional sports teams are not like other businesses.. especially the football operation.
In other businesses.. "staying the course" where you provide a product or service and understand your product or service very well, an organization can easily sustain.
Professional sports? Every season is it's own animal, like we've just seen. In the best of times, you're losing top talent on the coaching staff.. and you will continue to lose people on the coaching staff. The HC is the biggest constant on most teams.
It takes DYNAMIC leadership, every year, to succeed in the NFL. You can't just establish systems and keep course.. not with the football operations.
Business operations and PR and that kind of stuff? Yeah.
But not on the field