Fans and boxing experts scoffed at Floyd Mayweather Jr.'s decision to face Andre Berto for what he claims was the last fight of his career. And less than a week after the undefeated boxer tied Rocky Marciano's record of 49-0, Yahoo Sports reports that the pay-per-view numbers from the fight have been disappointing.

Citing a source, the report says that the Sept. 12 bout sold roughly 400,000 PPV units, which includes sales from DirecTV. A separate source close to the promotion of the fight estimated the figures to be between 500,000 and 550,000.

Whichever the case may be, it would be the lowest figure for a Mayweather fight since 2006 when he fought Carlos Baldomir on HBO PPV.

"To a large extent, anything we did coming off of that massive May 2 event was going to feel like a bit of a letdown," Espinoza told Yahoo Sports. "We didn't have available a really compelling list of available opponents. There's been a lot of speculation about a lot of things, but when you got down to it, there wasn't really a long list of available guys and none of them were slam dunk established stories or really compelling storylines."

Mayweather's May 2 fight against Manny Pacquiao sold a record 4.6 million PPV units, and generated a massive $400 million in PPV revenue. The dissatisfaction from the most expensive PPV boxing event, though, was nearly just as big.

"At the end of the day, given what we've accomplished, we're essentially competing against ourselves with this," Mayweather Promotions CEO Leonard Ellerbe said. "There's no one else at this level, so we're just competing against ourselves."

According to Yahoo Sports, while the live gate hasn't officially been announced, Ellerbe said it would be at least $10 million. The announced attendance for this past Saturday's event was 13,359 - 1,000 short of a sellout.