Because you apparently missed this the first few times I've posted it: I have no problem with Allen. My question has, and continues to be, why Obama felt it necessary to "outsource" this.
Further, your comments in this thread indicate you have military experience; but your fundamental mis-understanding of the role of the JCS makes me wonder just how much experience. If you'll look up even a Wikipedia article, you'll find that the JCS' primary role is to advise the SECDEF and other executive offices--including POTUS--on military matters.
Thus, my question. POTUS already has a dedicated group of active military members who are identified by statute and appointed by POTUS himself to advise him on such matters. Yet he pulls a retired Marine to advise him instead.
Now do you understand my confusion?
I think I understand your confusion and I think we are just talking past each other. When Odierno oversaw Iraq he actually lived there. The Chief of Staff remained stateside to advise the President and oversee the Army as a whole to include all sorts of things like policy, recruiting, finances, etc. Two separate jobs! I'm willing to bet that Allen was recommended by one of the JCS's. Allen wasn't hired to advise the President. That's Odierno's job. Allen was hired to oversee the "war" and spearhead the formation of a coalition. There are approximately 40 countries that have expressed a willingness to oppose ISIS but like the U.S., they are hesitant to put troops in harms way. That by default implies that he will report to the JCS's because they will be the ones authorizing the assets to be used. Im sure Allen will advise all of them on his strategy, progress, needs, etc.
What I don't know is if Allen is actually going to set up shop in the embassy in Baghdad. This campaign is a little bit different. I suspect that much of the strategy will be utilizing his past relationships in Iraq to set up intel sources in the area. I would think he would need to be there to do that.
Bottom line is that he is the right guy for the right job. I don't know what else to tell you. Even in the last two conflicts in Iraq and Afghanistan, retired officers were present in a myriad of ways. They instructed at the COIN academy, taught tactics and advised on tribal relationships. Allen retired in 2013 as the top Commander of Afghanistan so he is still very relevant.
EDIT: I forgot that ADM Mullen was replaced by GEN Dempsey, USA as the Chairman of the Join Chiefs of Staff so Odierno is technically the second highest ranking Army officer.