Back to the concept of the book. There were many disagreements within the CSA government, the state representatives, and local politicians. They fought over troop deployments, funding, resrouces, etc. CSA management was not exactly united. Anyway, I don't see anything new with this.
W.C. Davis and the Bruce Catton have done a thorough job documenting the dynamics and politics during the formation of the CSA.
Grant was a wise enough strategist to know that numbers could only be a positive factor if he harried the enemy enough to prevent him from adopting static defenses that would neutralize his numerical advantages.
So his strategy was not just mindless attrition or butchery - it was a strategy of continuous tactical engagement for the strategic purpose of eliminating the adversary's defensive advantage.
Had Lee been a commander of average rather than exceptional skill, the casualties lists would have been much more even.
Back to the concept of the book. There were many disagreements within the CSA government, the state representatives, and local politicians. They fought over troop deployments, funding, resrouces, etc. CSA management was not exactly united. Anyway, I don't see anything new with this.
That isn't the book's thesis, although you are absolutely right to say that neither the divisions within the Confederate government nor the book's actual thesis are new.
The book's thesis is not just that there was dissension among Confederates, but that there were plenty of Southerners who did not consider themselves Confederates - these were not Southerners who were merely dissatisfied with the policies or actions of the Confederate government, but Southerners who were opposed to the existence of the Confederate government in the first place.
Plenty of Southerners refused to sign up to fight their country - i.e. the United States. There were plenty of white non-slaveholding farmers in Arkansas, Georgia, Tennessee and Alabama who had a lot more in common with white non-slaveholding farmers in Wisconsin, Indiana and Pennsylvania than they had in common with the wealthy planters in Charleston who started the whole secession business.