So hard to call - like others point out, JDS has taken significant proportions of physical punishment, repeatedly (decent amount in his interval wins of Stipe & Hunt as well for 5 straight fights). I love JDS for his heart and entertainment value but I'm not sure he'll ever be the same. That being said, Rothwell looked rather sluggish in his last fight as did Barnett. Have to admire Rothwell too for the same reason.
Imo: If Rothwell hurts JDS early, he wins the fight. If JDS can keep the distance and not engage in the clinch much, wear Rothwell down with a steady pace and not try to KO him, he can win. Just hope its entertaining lol (how can it not be? its probably not going to decision)