Auburn won the national title in 2010 and then last year went to the national title game with a new head coach....Oregon has been a contender for several years under Chip Kelly and they have a new head coach and they are in the playoffs. You can make examples of both situations programs who tank for a few years and struggle to return to a contender and then others who just keep going as usual. Every situation is different.
I'm not saying Bob needs to go (this year) but I am saying he needs to do some house cleaning especially on the defensive side of the ball before next season. He should start by telling his brother to pack his bags and hit the road. He won't though.