Devin has the tools to beat Ryan, but he insisted on trying to walk him down. He should've switched up after the first knockdown, or even after getting stunned in the first.
He's got to accept that he just don't have that power like that. He's got many other skills, but that's not one of them.
Edit:
Could just be a styles make fights, Mayorga Vernon Forrest type of thing, too. The hand speed had Haney hurt against Linares, and he just faced a guy who didn't make weight and is a stronger puncher in Ryan.
Boxing.