You are exactly correct.
Look at Notre Dame. They have gone down since Lou left in the 80's. Sure in 2010 Notre Dame got lucky and got to the National Championship only to lose big to Bama Notre Dame is still not back
Texas has fallen since Vince Young and championship
USC has fallen since Pete Carroll left
Penn State was down during Joe Pa's last few year and the Bill O Brien years
With us being in a tough conference and with constant coaching changes, it will take forever for us to recover
Last week a Bama fan at work said. ( Tennessee is so put of sink, they even Saban couldn't turn them around