I don't really agree with this premise personally. See I fell into this trap when I picked him against Spann. I thought "Even if his chin got ruined by Jan and Jiri, he should still have all of the same technical skills that make him a fairly solid fighter and leagues ahead of Ryan. Short of a puncher's chance, he should box Spann up no problem, same way Smith did!"
Boy was I wrong. It's not like Spann "just caught" Reyes. Dom looked absolutely awful. Where he was previously known for his graceful, athletic footwork and the way he could bounce around the Octagon and mix up his shot selection, against Ryan we saw none of that. The dude was dragging himself around the cage, flat-footed, like he was stuck in molasses. Everything about the way he moved and struck was painfully slow. Not just that, but his decision-making was off, too: he was throwing naked body kicks with zero setup that were telegraphed from a mile away. He looked nothing like the guy who fought Jones and stormed his way up the division years ago; he looked thoroughly washed IMO, as crazy as it is to say considering he's a guy with fairly little fight mileage in the grand scheme of things.