Ok, I understand that Hancock & Reynolds weren't yet corps commanders through the commands of Pope and Burnside. But what about during Hooker's and Meade's? Which brings up an interesting thought: would either Hancock or Reynolds have followed up at Gettysburg with a more vigorous pursuit than Meade's? I tend to think Hancock might have.
Supposedly Reynolds was offered command of the Army of the Potomac before Meade but turned it down. Meade was senior to Hancock and had a solid, if unspectacular, record. He was a good choice for the army and had he been in command at Chancellorsville the outcome might not have been as disasterous as it was. Hooker was a puzzle. He was a good corps commander before and after Chancellorsville and on paper there was no reason why he was a bad choice as army commander.
It's possible that either man would have been more aggressive after Gettysburg but they may not. After Gettysburg the army was worn out, about a third were casualties, artillery and wagons were pretty beaten up. It's possible that they may have let Lee escape as well.