Former bantamweight, super bantamweight, and featherweight titleholder Abner Mares has bounced around weight classes over his young career, but has always moved up in weight, to the point that he had to make an announcement that he would be staying at 126 instead of moving up to 130 after his first career loss last year.
However, he did say during Carl Frampton's win over Kiko Martinez that he might consider dropping back down to 122 pounds to face Frampton, the new IBF titleholder:
Mares (27-1-1, 14 KO) last fought on July 12, beating Jonathan Oquendo handily on the Canelo-Lara undercard. That fight was his first with trainer Virgil Hunter, who seemed to instill more patience in Mares, who wasn't his usual action-oriented self.
That said, Frampton-Mares certainly sounds good to me, and I can't imagine anyone not wanting to see that fight. Whether it has any realistic chance of happening -- Mares is now with Al Haymon, after all -- is another story.