Absolutely true Bob.  Where did all those seasoned, administratively and organizationally  trained Baathists, the Sunni Muslims,  go when they got turned out by GW Bush.  Nowhere.  Some dispersed, but the rest formed the backbone of ISIS, in 2006, and are much more powerful and purposeful than al Queda.  I think these people are angry, Bob.  They have long range plans and a modus operandi that is a kind of 'shock and awe'.   Hopefully, they are in their descendency.