Mayweather didn't decline much. His defensive/safety first style ensured a long career w/ minimal slide in his reflexes and abilities. If he came back, he'd have ring rust, but he'd be pretty close to prime if he actually went through a real training camp (unlike the McGregor farce).
Yea I wouldnt say he ever declined. Just got older. The 1st Maidana fight proly took a little toll on him but came back to decisively win the rematch. Sharpe his whole career
First visible decline is when he got whooped by Castillo. Second, is when he got whooped by Maidana. And last is when he got hooked on saline. So really it's a triple dip career.
Almost everyone declines by mid 30’s but can extend their performance by years if they supplement testosterone intelligently.
He didn’t, people bring up Cotto or Maidana but that’s just credit to them for being good fighters with the right style to give Floyd a tough fight.
Around Maidana time but his ring IQ is just insanely off the charts he adjusted and was still a force. As for the McNugget fight, Floyd carried him for 10 rounds to give the promotors their money's worth. He could have KOd that guy in the first minute if he wanted to.