That's a bold statement. For a technical stand point he was very, very good and one of the best inside, defensive fighters of all time, but he wasn't perfect. He wasn't a great mover, not flat footed but movers gave him problems and he relied a little too much on his right hand counter, when a fighter took that away like in the Griffin rematch he looked less effective.
Certainly not the most skilled but I am would put him in a top twenty. When u look at his career and some of the guys he beat u can't knock him for that but then u look at the losses. He should nt have lost to a few guys early on or struggled like he did
Tough to say, Monzon, Hagler, Hopkins, are all candidates so I would place Toney in my Top 3 which is saying a whole lot about his skill set.