He really wasn't, if he was a Cuban B-side he'd have been forced to fight the best at their best his whole career and we wouldn't even be having this discussion because he'd have been beaten multiple times like his Dad and Uncle. By virtue of being an American, and talking a lot of smack he was able to get into the position of choosing his opponents. From there he hoodwinked boxing into thinking he's better than he really is.
Floyd's last fight was against the other greatest fighter of the era, his next fight - his last - is against a hand-picked, over-matched opponent. The circumstances are identical. What's so hard about this for you to understand?