Mayweather came out of a two-year retirement at age 40 to take on UFC 155-pound champion Conor McGregor, because who wouldn't return from a two-year layoff at age 40 to earn, when the cash register stops ringing from the fight, perhaps $300 million for one night's work in another record-breaking event?

Mayweather put in real work, too, on his way to a 10th-round technical knockout of McGregor, a novice boxer making his pro debut in a fight that was wholly illogical -- which was probably one of the reasons millions of people were so intrigued.

But even though Mayweather won -- and easily after McGregor captured maybe three early rounds -- the fact that he had any problems with McGregor whatsoever was a sign he is no longer the fighter who once dominated one star fighter after another, such as Manny Pacquiao, Canelo Alvarez, Oscar De La Hoya, Shane Mosley and Miguel Cotto.