Keith,
They did get a good "whooping", as you say, at Chancellorsville, but I doubt if any of the Union Corps of the AOP, struck directly on the flank, by surprise, with overwhelming numbers, would have fared any better. The exposed and flanked position of the outnumbered 11th Corps at Gettysburg, was again, more a matter of poor leadership and a resulting poor morale, than the quality of the men. Just my opinion.
Jim