In recent NFL history what team or team's halve started over almost from scratch like the Jag's are doing and how long did it take for them to be competitive again???????????
The 4 most recent and obvious examples of a coaching change and solid amount of roster turnover would be the Texans with Kubiak , the Lions with Schwartz, the Skins with Shanahan, and the Saints with Sean Payton.
The Jags rebuild is cutting deeper and wider than these however.
I sort of ran the numbers a while back and basically having a really bad record one year isn't a very significant indicator of the next years record.