Hopkins hasn't KOed anyone since 2004 (a blown-up welterweight in DLH). What makes you think he could KO Roy Jones Jr. now? You can't compare Hopkins' power to Danny Green's, who has Miranda-esque type power.
Also, he gave up 4 round in his last fight against Enrique ****in' Ornelas, and didn't even come close to stopping him. Now he's going to KO a guy who's still much faster and more skillful than Ornelas? RJJ by UD, by the way (115-113ish). Styles make fights, even when the fighters in questions are long past their prime years.