1b) As bad as it would be to lose Grant and Sherman, there remain: G. Thomas; CF Smith; AM McCook; HG Wright; DC Buell; Rosecrans; AJ Smith; Sheridan; Canby; etc. All have both weaknesses and strengths, but come on - AS Johnston? Bragg? Price? Polk? Hardee? (okay, maybe Hardee)...
Even Union commanders who were losers in Virginia - Burnside, Pope, Pleasanton, were winners elsewhere. It says something when Bragg was probably the second most successful Confederate commander.