I've always thought that the softer politicking in the Army of the Potomac, as such that got John Pope an army command and saw a real whirligig of command in 1863, were always ripe for the dysfunctional infighting that tore the Army of the Tennessee to shreds. Here, without more direct oversight from an omnipresent government, and the horrifying prospect of defeat, I think I found just such an occasion for the more toxic elements of the AotP to scuttle into the light. Hooker was an obvious candidate, but I don't think Rosecrans would have sat well under McClellan's command either.
With friends like these...