A friend of mine makes an interesting point. Battle of the Wilderness was similar to a chessmatch between two masters. His numerical strength was not overwhelming. After play and counterplay, block and counterplay again, it was Grant who gained a wedge up the middle and forced Lee to retreat. At the Battle of Vicksburg, his strategies were excellent. He's a tad under-rated sometimes.
Grant's foremost strength in confronting Lee there was that (unlike all prior commanders of the Potomac Army) was that he did not back off in the face of casualties. Lee had perhaps become spoiled by the lack of stomach on the part of prior Union commanders he had faced. Lee is still better, don't get me wrong, but Grant was a lot better of a commander than some historians give him credit for.