Are within-guideline crack sentences now presumptively unreasonable after Rita?

As I have stressed repeatedly before (most recently here), the US Sentencing Commission has said officially, repeatedly and emphatically that the current crack guidelines are too harsh and thus "significantly undermine[] the various congressional objectives set forth in the Sentencing Reform Act."  (And, as detailed here and this archive, the USSC has this year put its long-held expert opinion into action by amending the guidelines, effective November 1, to lower all crack guideline ranges across the board.)

In Rita (opinion here), Justice Breyer's opinion for the Court speaks approvingly of arguments from counsel that "the Guidelines sentence itself fails properly to reflect §3553(a) considerations" and/or that "the Guidelines reflect an unsound judgment."  The Rita opinion for the Court further explains that "where judge and Commission both determine that the Guidelines sentences is an appropriate sentence for the case at hand, that sentence likely reflects the §3553(a) factors (including its 'not greater than necessary' requirement)."

Adding all this up — and again keeping in mind the USSC's own official, repeated and emphatic assertions that the crack guidelines are "greater than necessary" to achieve serve §3553(a) — shouldn't a circuit court view a within-guideline crack sentences as presumptively unreasonable?  Of course, after Rita, a district judge surely would have discretion, in the course of "exercising his own legal decisionmaking authority" to explain why he or she believes that, on the facts of a particular case, a defendant's sentence should be within or even above the current crack range.  But, unless and until a district judge explains why it is imposing a sentence that the Commission has officially, repeatedly and emphatically deemed inappropriate, I think that sentence logically ought to be reversed as greater than necessary.