First, we should understand that all generals (certainly at the 3-4 star level) are political. There is no such thing as the apolitical general except in fiction. So their coming-and-going always must be looked at from a political as well as professional aspect. Don't know about Allen but Petraeus has had many detractors, inside and out, both over what is seen as his politicking as well as professional dislike (if not distain) for the COIN doctrine and strategy with which he is closely identified. Kind of surprised to see "making us fight with arms tied behind our back" townhallers supporting him now.