Apart from Mayweather & PacMan boxing has no superstars

[Hulk]

Would anybody disagree.

Bad for the sport.

Disagree.

Sergio Martinez is quite a super star.
Amir Khan, Carl Froch, Klitschko brothers are all quite famous.

The average American has no idea who any of those people are, I assure you. *Maybe* the Klitchkos would ring a bell if you gave enough context. The others, no way. I like all of those fighters (particularly Martinez) but none of them can even headline a PPV fight.

Does the average American have a clue of who Floyd Mayweather is, or better still, Manny Pacquiao?

Yes, actually. Plenty of people I work with who have not seen a fight in the last 20 years know who Mayweather is and know that he is considered the best today. They would have absolutely no idea who any of the people you mentioned is -- except possibly the Klitchkos. Look, Mayweather is the consensus best fighter in the sport. He was on Dancing with the Stars and was in Wrestle Mania. He got coverage for spouting off about Jeremy Lin. He got coverage for going to jail. He had f'ing Justin Beiber as part of his entourage for the Cotto fight. He's a mainstream figure. People who know nothing about the sport know the name.

Manny is slightly less recognizable but he is on Nike and Hennessy commercials shown on TV in the states. He makes appearances with candidates running for American political offices (as absurd as that is). He's mainstream.

YES !

Most everyone knows who Floyd and Manny are.