DuBoef said Gamboa had agreed to the Rios fight and that he has an ample paperwork trail to back it up, even though the official bout agreement isn't signed yet. (It's standard practice in boxing for a formal bout agreement to go unsigned until well into a promotion.)
I've actually thought about this hookup before. Gamboa has good defense, but he has mental lapses and loses focus sometimes. He already uses a version of the shoulder roll. If he gets with Roger, he can fix all that and be better suited for the higher weights