why do people think RJJ was PRIME when he first fought hopkins?

RJJ became a better fighter when he moved to 168lbs you could clearly see jones had better movement and became a better boxer. the other question i wanted to ask you guys is. when Roy came back down from heavy weight. he seemed to have lost that power he had before moving up. i remember the times when RJ would hit his victims with the first left hook and u could see the damage it would have on his victims causing them to go into a shell. at 168lbs he had 1 punch knock out power in both hands. and i would have to go on to say if Jones had landed the same punches he landed on Calzaghe. when he was PRIME like the uppercut he caught Joe with would have dropped Joe and caused the fight to be stopped the same round