I'd say they have both slowed and aged and the same amount. May the best man win and no excuses after! from the fighters or the fans!
While both fighters are clearly past prime, we could still make the argument that they would still beat all the top current 140-147 lb fighters so I really don't get why we are still having this debate about both guys being past prime. They are still the 2 top fighters in or around 147 lbs., past prime or not.