He wasn't a good combat officer. It was hard for him to realize that once the battle is joined, the commander cannot achieve much. The subordinate officers have to co-ordinate with each other. With respect to the rest of things that the commanding officer must do, he was brilliant. One of Rosecrans' problems was that the Cumberland theater did not have the Atlantic coast, the eastern railroad network, nor the Mississippi River. His department was not a high priority, and all the logistics there were more expensive. The Kentucky and Tennessee railroads were making his situation difficult. Those problems began to be solved when Grant took over in that area, and then Grant and Sherman planned the Georgia offensive. The eventual victory at Chattanooga won by Rosecrans' former army benefitted from improved logistics once Meigs went there and the US militarized the railroads.
Grant acknowledged that Rosecrans' plans, including building steam barges on the middle Tennessee River, were excellent.
Rosecrans may not have obtained the special forces units he advocated, but it seems that they did exist in Army of the Ohio. And Sheridan's cavalry contained many troopers who would wear Confederate uniforms and learned how to speak "Confederate".