Prior to Grant Lee was on the offensive and did quite well mostly due to inept Generals and officers of the US army. During the Overland campaign Lee had the advantage of knowing the geogrpahy - and being entrenched more then 90% of the time. Whereas Grant, by the nature of being of the offensive, lost more men. And having Butler and Sigel screwing up his plans didn't help matters. Keep in mid while you are addressing "Grant helping Lee kill all those yankees" that Lee lost more men in the entire war my % and raw numbers then Grant did.