The Confederates had to play a perfect game. Grant didn't. All he had to do was shove men into the meat grinder and eventually they would win.
IMO: Grant was very adept at maneuver warfare he showed that in the Vicksburg campaign. When he came east he realized the Army of the Potomac was not the Army of the Tennessee. Where before he had a rapier, now he had a big heavy club. And that’s how he used it.
“When you have a four to one manpower advantage, and a huge industrial base to back you up, it’s inevitable that you will win in the long run.”
McClellan, Burnside, Pope and Hooker all had those advantages, did they win? Being able to use those advantages to gain victory is Generalship.
The end goal of the CSA was to never conqueror the USA. It's goal was to leave the union, not conquer it.