I agree with your line of thinking, but think that combat fatigue, shell shock and war wearriness are all different maladies featuring some common symptoms.
"I have no more generals. The cold of Moscow has demoralized them. I have seen the boldest cry like children. They were physically and morally broken." Metternich's version of what Napoleon said during their 9 hour armistice discussion in 1813.
"He found fault with himself for having made so much use of the marshals in these latter days, since they had become too rich, too much the grands seigneurs and had grown war-weary. . . ,would have been in a much better state if he had placed good generals of division, with their batons yet to win, in command." Caulaincourt
"I remember well to have heard several generals blame the Emperor at that time (1814), because he had not abandoned Spain and recalled all his troops to France". Constant
Personally I think Messina was war weary. Possibly so was Augereau.
Junot and Marmont may have been shell shocked to some degree (not in the classic WWI mode). Ney is a good candidate for combat fatigue and Davout may have had a touch of it too.