I don't know much about boxing, or MMA for that matter, but from what I saw it did look as if Mayweather was basically taking it easy and keeping away for the first few rounds while he figured things out, and until McGregor got tired. Around round 6 or so he started attacking and the real balance of the fight became clear.
Also, is there any chance Mayweather was taking it easy to draw the fight out so that it would last long enough to be thought of as worth the hype and money it cost to watch? Also, that maybe they had a deal where he wouldn't embarrass McGregor? The match is kind of a joke, right? So it isn't like it had a lot of integrity to spoil. I'm not a regular fan though, so I dunno how likely that is.