Lol, what fighters do you like Mars?

It's hard to assess Jones career in large part, because we really don't know when his skills started to diminish and to what extent, or whether moving back down in weight was really as devestating as is often made out.
For me this excuse is kind of trumped by the fact that he looked a lot fresher in the first round of the Tarver rematch than he did in any of their first fight. He simply got caught with a great punch, but also one of the only truly great punches he'd been hit with in a long time, and it knocked him silly. He clearly never had the same confidence in his abilities after this, whether they were there or not. Leonard in his prime fought the kind of opposition that you can't go without being hit by, and sure enough proved to be extremely durable all the way through. I think SRL is more of a concrete entity for this reason, you have a reasonable idea about how he might have fared against certain guys he didn't fight, which isn't so much the case with Roy imo.
Often times with slick fighters it's once they lose a step that you start to see how tough they really were, Pernell Whittaker for example proved that he had a hell of a chin against Trinidad, nobody could've guessed whether he would stand up to that kind of punishment before the fact.