Bruce Buffer -- Crappy Mayweather Fight ... Was Great for UFC!!!

The Mayweather vs. Pacquiao fight was so bad, it actively HURT the sport of boxing ... but it was GREAT for the UFC ... so says UFC octagon announcer Bruce Buffer.

Buffer -- the voice of the UFC -- was brutally honest about the fallout from the bout that was supposed to be the fight of the century ... saying it was a HUGE flop.

"When you create something with so much hype, you have to deliver. And if you don't deliver, then instead of getting a shot in the arm, you get a shot in the leg."

"That night was really a shot in the leg for boxing in my opinion and a shot in the arm for UFC."

So, why was it so great for the UFC? Check out the clip.

BONUS -- Buffer also addressed criticisms from people who say UFC fighters are underpaid ... saying Dana White has done a helluva lot to make sure the checks are bigger than ever.

Buffer also mentions how much Rampage Jackson got paid for his first fight back in the day ... and the number is pretty shocking!!!