Its not about expectation more so than how the fight translated, Mayweather wasn't fighting like he has in the past and every indication looked like he wasn't in any serious danger the whole fight, even refusing water in the corner between rounds.
There was no indication that Mayweather was even trying to go for the early knockout.
Not a knock against McGregor(as stated multiple times already) but Mayweather looked like he could easily go another dozen rounds no problem.
Mayweather is a marathon fighter in a marathoners race, McGregor is a sprinter that people paid good money to see fight. I don't see how the fight was going to translate any other way.
It was a plan, executed to perfection on Mayweathers end.
And for the last time, yes McGregor would beat Mayweather in the octogan fast because that is how the game is designed. Two different skill sets required.
This whole spectacle was orchestrated based on the premise of legitimizing MMA fighters as experts in every combat sport they incorporate.
In this case, boxing.
Speculators picked up McGregors stand up wins and debated he legitimately could stand a chance against the best professional stand up boxer.
Putting aside Conor's accomplished UFC career and all its hype baggage, he demonstrated exceptional talent in the ring against the best ever, despite tremendous lack of experience and boxing technique.
In an ideal world, I'd like to see Conor stick with boxing.
Better yet, put the pre-fight egos aside, and seek Mayweather out for further mentorship.
Floyd always speaks about legacy, and having schooled the rough around the edges UFC champ, it would be incredibly exciting to see a Mayweather trained Conor McGregor take on the boxing world.
Edit:
I find UFC to be disappointingly boring, because despite bearing the Mixed Martial Arts motif, most UFC fights boil down to brawlers sizing each other up for a knock out punch and hammerfisting their way to a win.
The only thing exciting about UFC was McGregor and Jon Jones, because they faced trained opponents as confident martial artists and executed exciting moves and maneuvers.
But the sport isn't all its cracked out to be, as demonstrated by this crossover.
(In my idealized movie world, I'd love to see highly technical, lightning fast exchanges and counters spanning a variety of styles...but alas, they sport is not at that level.)