Floyd Mayweather Jr. is widely regarded as the best fighter of his generation and one of the best defensive fighters of all time.
He enters his May 2 fight with Manny Pacquiao with an undefeated record of 47-0. There's a case to be made that Pacquiao can pull an upset, but most expect Floyd to win this fight the same way he has won fights for years — making his opponent miss early, timing his counters to perfection, and eventually winning on points.
There's a radical juxtaposition between Mayweather's persona out of the ring (obnoxious, offensive, appalling) and his style within it (calm, intelligent, pragmatic). Over the years the fighters who've lost to Mayweather have spoken about his boxing brilliance in glowing terms, and explained what makes him so hard to beat.
Ricky Hatton (lost by knockout, December 8, 2007)"I was fighting a genius, a boxing artist. I was getting more and more frustrated. Lose your cool against Floyd Mayweather and what you do is you get knocked out." — to Showtime
Oscar De La Hoya (lost by split decision, May 5, 2007):"Now we have to give credit to Mayweather because what Mayweather can do is what Mayweather Sr. calls 'walking your opponent down.' So what he does is he gets in the pocket and covers himself and he'll walk you down. And he'll let you throw punches and Pacquiao is probably going to keep throwing punches in bunches and he might tire himself out while Mayweather is just blocking everything. And then Mayweather can just come, throw his combinations of two or three punches, win the round, put the rounds in the bag, and win the fight." — to HBO
Canelo Alvarez (lost by majority decision, September 14, 2013)"He doesn't expose anything. He's a fighter that if with three punches he wins the round from you, he's fine with that. He doesn't expose anything and give a beautiful fight. He doesn't care in what way he wins as long as he wins." — to FightHype
"He's very fast and accurate and moreso when he's just trying to make points. I didn't really feel his punches were that strong. But he's making points and he's very fast." — at his post-fight press conference
Shane Mosley (lost by unanimous decision, May 1, 2011)"I felt that I had the advantage on Floyd. I was very certain that I could hit him with good shots and I thought that could be the difference. I caught him when he thought that he was out of the way. I kind of slid it, a veteran move, and caught him right on the button and rocked him. He was surprised and I was like, 'Wow, this is my chance. I'm going to get him. I'm going to knock him out.' But I just couldn't. He made the adjustment. He was able to capitalize. After that the fight was over. Mayweather did what he was supposed to do as a champion to win." — to Showtime
Juan Manuel Marquez (lost by unanimous decision, September 19, 2009)"Mayweather has had great defense, long arms, and he's very smart." — to Showtime
"Mayweather’s reaction time is amazing. He sees what you are about to throw and is out of there before you can punch." — to WSJ
Zab Judah (lost by unanimous decision, April 8, 2006)"His defense is still impregnable, his hand speed is still super fast, his conditioning is always marvelous. What can you say? The guy, he’s probably one of the hardest working fighters in boxing." — to Mark Giongco
Paulie Malignaggi, who thinks Mayweather is going to beat Pacquiao, gave this great description of Mayweather's defensive skill in 2013 before the Canelo fight (via Yahoo's Kevin Iole):
"He makes you miss a lot in his fights, but he doesn't make you miss the same way. If he made you miss the same way all the time, guys would start timing it and start hitting him. He'll make you miss the right hand in different ways. He'll make you miss the left hook in different ways. … He varies the ways he's able to defend and that is what makes him so difficult."
While there's an argument to be made that Pacquiao is a tricky matchup for Mayweather, there's a reason Mayweather is undefeated, and a reason he's a significant favorite to remain that way on May 2.