Julia Ioffe points out the big flaw in firing Hagel:
All of this adds up to a rather strange way to address the criticism leveled at the administration’s foreign policy: If you fire the guy least responsible for it, it’s essentially a doubling down on what you’re already doing, thereby denying there’s a problem with it.
That confirms the view that Hagel has been made a scapegoat for administration policy failures that he had little to do with, and it tells us why replacing Hagel probably isn’t going to lead to any significant changes in policy. Dumping Hagel is a way of appearing to shake up the administration following the midterms without doing anything that would change the way that the administration operates. Superficially, it mimics Bush’s firing of Rumsfeld, but in some respects it represents something very different from it. Instead of holding the official most responsible for a failed policy accountable for his errors, it gets rid of him because he has been relatively unimportant in shaping administration policy.
Where Rumsfeld was removed for being too stubbornly committed to his chosen failing approach to a war, Hagel seems to have been pushed out because he was becoming somewhat too critical of the administration’s aimless prosecution of a war. The firing of Hagel fits into a pattern of odd and dubious decisions by Obama that the president has made, the main purpose of which seems to be squelching domestic criticism. There have been many calls for a shake-up in the administration’s national security personnel, and so Obama has obliged by throwing Hagel overboard on the mistaken assumption that this will satisfy the critics, but it doesn’t mean that Obama intends to make any changes to how his administration makes policy. Of course, this won’t satisfy the critics, and just creates another reason to question Obama’s decision-making on these matters.