Don't forget Pacquiao was well past his prime when he fought Mayweather, and was distracted by politics. In fact Mayweather wouldn't fight him in his (Pacquiao's) prime. This is the theme of Mayweather's career - everything has to be right for him. And this is partly why he'll beat McGregor.
Though I hope I'm wrong.
RE: I Don't Think Mayweather Would Throw The Fight (It's Possible, of course, but let me tell you why it's not likely) And I Still Think McGregor Will Lose