I can't imagine anyone doing a better job than Samuel Cooper and he was certainly well known in antebellum society and the army. Importantly, he was adjutant and inspector general of the United States for almost a decade before the sectional crisis erupted and, together with his brother-in-law, Robert E. Lee, deserves much of the organizational success of First Manassas (Lee with organizing the Virginia troops that were absorbed into Confederate service by the central government on June 8 1861, and Cooper with providing order and systematic overseeing of much of the uncoordinated movements of troops leading up to that battle).
But much more than that, Cooper had encyclopedic knowledge of hundreds of officers and politicans, and managed to be as one described him "clear-headed and without prejudice"--- the prefect description for someone in the position of adjutant general. Cooper got along well with his superiors while at the same time was a buffer between egotistical generals and the president as well as (whoever was the current) war secretary. Bottom line, Cooper was greatly respected by most and was an integral part of the Southern war effort.
Having gone through his papers along with the preserved parade-states and circulars of the Army of Northern Virginia at the National Archives during many visits there, I am eternally grateful that General Cooper was extraordinarily well-organized. When Cooper left Richmond in April 1865 with the fleeing government, he had carefully packed up all his records. When Davis released him following the flight from Danville, Cooper surrendered, and with his parole turned over to Federal authorities all his records that are today, in essence, the Confederate War Records as preserved in the National Archives and Administration in Washington D.C.
So to answer your question, no one was better qualified to be adjutant and inspector general and I can't imagine anyone doing a better job.
By the way, if memory serves, Cooper was a New Jersey native. With his marriage to George Mason's granddaughter, he soon became an adopted Southerner.
Regards,