Let's agree that I am pretty much the last guy on the planet to have useful insights into l'affaire McChrystal, but I do have one thought that I haven't seen on offer anyplace else.
That is; whatever his virtues, McChrystal strikes me as precisely the kind of guy who is going to attract yes-men and bootlickers eager to warm themselves in his alpha glow. This is one place where the MacArthur example may be relevant: the MacArthur apparatus was teeming with these bleating yea-sayers happy to do whatever they felt necessary to enjoy what they perceived (correctly?) to be their best protection in life.
The mere fact that he attracts these pipsqueaks is not McChrystal's fault (nor MacArthur's). The question is what he does with them: does he flic them off like a fragment of lint from his lapel? Or does he let them hang around and tell him (and everyone else) what a great man he is?
Never having enjoyed the luxury of a flock of toadies, I can't say how I would respond to the warm bath of constant approbation--I imagine it is pretty seductive. But it may that McChrystal's chief deficiency is that he didn't have the strength of character to tell them to buzz off; that instead he sat by and sniggered while they talked him into a career-ending punji trap.