Most fighters by the time they are 35 are on the downside of their career.
Boxing is a hard game and constantly having people hit you in the head for many years doesn’t lead you to get better as you get older.
Most people don’t even realize that Mayweather is that old. He isn’t in his prime anymore, but he is so talented it is hard to notice any slippage.
Mayweather has some Bernard Hopkins in him, he has subtly changed his style as some of his physical skills have diminished. His boxing IQ is very high.
In his younger days he was in constant movement around the ring, it was hard to hit him at all because of the fluidity and speed of his movements.
As he has gotten older, he has become more aggressive. It leaves him open to get hit more, but it also has made him a more interesting fighter.
He has an underrated chin, he isn’t Glass Joe like Roy Jones, he takes a pretty good shot and even though he “parties”, he doesn’t drink or does anything to damage his body.
Probably will be more appreciated after his career is over.