The theme here is the way McKiernan was treated for no apparent reason. He could have gotten something like a good award, ceremony, and another equivalent job, if not, a desk to hold down, even if early, this would be better than having to wear bus tire track marks for the rest of your life.
Yes, he did get thrown under the bus. He is certainly not deserving of that kind of treatment. He provided super leadership (from personal knowledge) in the buildup to and the invasion of Iraq.
I disagree that there is "no apparent reason." I think the method of his dismissal was intentional, and that implies (to me) that it was intended to send a message, most likely to the Afghans.
The undercurrent here is that the Afghans are complaining about civilian casualties. As Yon points out, "accidental mass carnage from our side is turning more and more people against us." That's what guerillas want -- it's how they win wars.
Whether those numbers are inflated or not is beside the point; the important thing is how those things are perceived by the Afghans.
What I expect we'll see McChrystal and Rodriguez using this public firing as a springboard to some sort of quick alteration in tactics -- something to show that we take these civilian casualties seriously.
Similar to Iraq, it will probably involve moving American troops into closer contact with Afghan locals, and forcing the Taliban either to leave, or to commit atrocities that have large civilian body counts.