I don't think thats a fair assumption to make... Look what Lovemore N'Dou did against Cotto. Tough guys give all but the best pure boxers a difficult fight. If Mayweather had foughten Forbes he would have easily outsped and outfinessed Forbes, but when its somebody a little slower like Oscar who isn't as good at moving or boxing then it becomes more difficult for them if they can't take out their opponent. Cotto ran into it a few times as well.