Age doesn't always tell the story. Some guys are shot by their late 20s, others labor on into their late 30s with lots of skills remaining. While neither guy is at his peak, IMO Mayweather is closer to that than Pacquiao. The other issue is that Pacquiao's power has not carried over well. Welterweights don't seem to be worried about Pacquiao's power.
There will be a rematch that Pacquiao will be designed to win.
I doubt such shenanigans are going on. Sometimes, you have to go with the simplest explanation - at this stage of their careers, Mayweather is a better fighter. Whether he was at their primes is still an open question in my opinion. Sometimes, I think that some boxing fans are blinded by Mayweather's obnoxiousness and under-appreciate his athleticism, his fanatical conditioning, and his all-around toughness and determination.
A salient point, and one that most people overlook. Mayweather is not a 'nice guy.' He is brusque, obnoxious and generally behaves in a manner that most people would not find a appealing. However, just because he is a 'bad' guy doesn't take away from the fact that he is one of the most tactical boxers in the world today. Manny Pacquiao is a better puncher, but Mayweather is easily a better boxer.
People who know the sport of boxing knew that Mayweather was ahead. Be they pundits, betting websites, or simply fans of the sport, it was clear by the 10th round that Pacman had only one option left ....knock Mayweather out.
On the otuer hand, mst people who don't follow boxing thought Pacman was winning because he was 'aggressive.' Unfortunately, aggressive doesn't mean much if the punches do not connect (only 19% of Pacman's punches connected). Ironically, Mayweather not only threw more punches that connected, he threw (overall) more punches!
Mayweather is not the type of guy one would leave their kids with for a Sunday school chat, but that seems to make many people overlook that as a boxer they're not many people that can conceivably take him on a good day. He is one of the best defensive specialists that have existed in the sport.