I don't disagree with this, but could you provide some examples? There is at least one major success that is obvious: Saban (MSU to Ala). Holtz did better at ND than Minn. Franklin is doing better at PSU than Vandy. Mason did better at Minn than Kansas.
On the other hand, you look at someone like Rich Rodriguez, or Bielema, and that's just laughable. They left perfect situations for temporary riches, and embarrassed themselves.
If anyone has a better breakdown of P5 head coaching moves, I think it would make for a great thread.