Why did Sugar Ray Leonard lose so BADLY to terry norris?

Alright so I know most people don't really rate Norris' win over Leonard because Leonard was shot. But what exactly made him shot? He hadn't lost in 11 years, and even if you thought Hearns won in the rematch, Leonard showed that he had plenty left in the tank. some reasons why people say he was washed: 1. he was coming off a year lay off. that does mess up fighters a little bit, but leonard only had 1 fight in 5 years prior to fighting Hagler, and he looked good in beating him. 2. he was 34. True, Most fighters aren't at their prime at that age, but he looked good at his last fight against Duran, who was coming off his Barkley win. He didn't look shot at all. Nor did he have several losses. At most he had 2 and none were knockouts. Norris got knocked out already! 3. he was fighting at 154, was drained. This what I was thinking, i believe a fighter always loses something when they move down in weight, especially when they get older. however, leonard rarely fought higher than 154. He was 165 against Lalonde, and 160 in the Hearns rematch and Duran rubber match. So it's not like he was moving down from 175 to 154 or anything crazy. Even though I have arguments why those 3 reasons may not have been the reason for leonard losing, I will admit that he did look like shit. did he just age overnight? what do you think