I mean, people can believe what they want.
Roy Jones Jr clearly lost a step (as do all fighters) from his early 30's onwards.
His success was predicated largely on his physical abilities and so a decline was inevitable.
I am simply stating that said decline was accelerated by his jumping up and down in weight classes at an age where fighters should really try and stabilize a single weight cut regimen.
I'm not disagreeing with you regarding cutting weight at a certain age but we didn't see any huge decline in Roy in regards to work output like we saw in Oscar, Chavez Jr and now that I think about it Chris Byrd too when he went back down from HW and looked like a skeleton of his former self.
Roy still had great output, fast hands.........the thing that damaged Jones was he lacked a true fundamental skillset on defense like Hopkins and Mayweather did and he was only able to get away from shots before and look impressive because of his reflexes, once they left him then we saw his flaws getting exposed more and more with the results being devastating KO's by guys like Glenn Johnson (not even a big puncher) who would've never laid a glove on Jones in Roy's prime.