On paper MecCellon(sp?) was a far better general then Grant. In peace time MeCellon was a far better General then Grant. War changes everything.
Rumsfeld has proven himself period. What is on paper is his actual performance. He's done it. He has run two Fortune 500 companies successfully and been SecDef twice, once in peacetime and once at war. Rumsfeld has the complete confidence of his boss and CIC, George W. Bush.