Where a court varies downward from a statutory maximum which is beneath the published guidelines range and the sentence is later further reduced on the government's motion, the sentence is not sufficiently based on the published range to merit relief after subsequent changes to that range.
http://media.ca8.uscourts.gov/opndir/18/06/164456P.pdf
Since 2011. An occasional commonplacing of the U.S. Circuit Courts of Appeal.
Neither an authoritative statement of the law nor legal advice. Quick work.