BTW, it's interesting in WW II that MacArthur has always been portrayed as the most "economical" of all the American commanders with the lives of his men. But the best of all was Nimitz, who had control of the central sector of the Pacific. Combined ground (island)/naval casualties under him were much lower than under MacArthur.
I think you are arguing that Lee was a poor general, because his casualty percentages were higher than his opponents, right?
OK, I count seven major battles for Lee:
1) Gaines' Mill June '62
2) 2nd Manassas Aug '62
3) Antietam Sept '62
4) Chancellorsville May '63
5) Gettysburg July '63
6) Wilderness / Spotsylvania May '64
7) Petersburg April '65
Of those battles, Lee clearly won three: Gaines' Mill, 2nd Manassas and Chancellorsville.
At Gaines' Mill, Lee outnumbered Porter by 80%, and suffered 13% casualties to Porter's 25%.
At 2nd Manassas, Pope outnumbered Lee over 50%, but suffered 26% casualties to Lee's 18%.
At Chancellorsville, Hooker outnumbered Lee over 80%, and suffered 16% casualties to Lee's 22%, though Lee's numbers were 4,000 fewer casualties.
Two battles were more-or-less a draw: Antietam and Wilderness / Spottsylvania.
At Antietam, McClellan outnumbered Lee nearly 50%, but Lee still fought him to a draw, while suffering 14,000 (27%) casualties to McClelland's 12,000 (16%).
At the Wilderness / Spotsylvania, Grant outnumbered Lee by 2/3 more troops while suffering 36,000 casualties (36%) to Lee's 23,000 (38%).
Lee lost two critical battles: Gettysburg and Pettersburg.
At Gettysburg, Meade outnumbered Lee by 8,000 (11%), while suffering 5,000 fewer casualties (28%) than Lee's 28,000 (37%).
At Petersburg, Grant outnumbered Lee over 2 to 1, and suffered over 2 to 1 casualties. Both had casualties of 8%.
Finally, we should note that Civil War statistics can be all over the map, depending on who counts, and who they count. Even so, I think the general picture here is on target.