Lee only compares to Grant.
Sherman & Butler do compare to lower ranking Confederates like Early & Stuart.
Indeed, if you think about it: Sherman under Grant at Vicksburg took on some general similarity to Stuart under Lee at Gettysburg.
And great website, by the way.
As you probably know, neither Lee nor Grant were the top commanders of their respective forces until near the end of the war. They got there due to their leadership and results.
Grant's promotion, as I recall, did not come until near the end of the Wilderness Campaign in 1864. Lee's maybe just a few months earlier.
Until then, they were outranked by men of far lesser ability.