If he changes his mind once his body and his ego have both healed up, he won't be the first. But if the 34-year-old former UFC heavyweight champ really has strapped on his last pair of 4XL gloves, what does his departure mean for the UFC and the sport of MMA? How will we remember Lesnar once we don't have the former WWE star to kick around anymore?
For UFC president Dana White, the answer probably has at least a little something to do with dollars and cents. Despite his inexperience in the cage, Lesnar immediately became one of the top pay-per-view draws for the organization after signing on in 2007. Whether it was because fans wanted to see him win or desperately hoped to see him lose, he put butts in seats and money in the bank for the UFC. He may not have always been the easiest guy for the UFC brass to work with, but he was a dependable cash cow.
And now, just like that, he's gone.
"I had no idea he was going to do that," White told reporters at the post-fight press conference. "Am I surprised? No. Brock Lesnar's made a lot of money in his career and he's achieved a lot of things. Brock Lesnar came to me one night here at the MGM and pulled me aside and said, 'I want to fight in the UFC.' I laughed. He was 1-0, came from the WWE, and he brought a lot of excitement to the heavyweight division. What that man accomplished in a short amount of time with one [prior] fight is amazing. I get it. It doesn't shock me, but I didn't know."
For the man who could turn out to be Lesnar's final opponent, the news seemed to come as more of a surprise, and maybe even a bit of disappointment.
"I think he shouldn't walk away, because love him or hate him, it's always something when Brock's fighting," Overeem said. "...He's a guy who goes for it. I think he achieved a lot in a short span, and it would be a shame if he stops now."
And yet, the Lesnar who got battered and beaten by Overeem didn't seem to be one who was burning up with an unquenchable competitive fire. He fought a reactive fight -- one devoid of the raw aggression he'd displayed in his earlier bouts. He never committed to getting Overeem to the mat, and a few well placed body shots sent him scurrying for cover. When Overeem whipped his shin across Lesnar's midsection, that was all it took to convince the former NCAA wrestling champ that it was time to cover up and go home, perhaps for the last time.
What does that ignominious end mean for Lesnar's legacy? Odds are it will only solidify the oft-repeated criticism that he never really got comfortable with being hit. When Lesnar was on offense, he was a juggernaut that mowed down everything in his path. But when an opponent managed to turn the tables he tended to shy away from the blows, going from attack mode to full retreat in a few seconds.
Some of that can be attributed to inexperience. After a pro debut against the thoroughly forgettable Min-Soo Kim, the bulk of Lesnar's MMA education took place on the job. He fought many of the best heavyweights around without the benefit of a gradual build-up or even much cage time in which to get comfortable. He was a star from the very beginning, and he was held to an almost impossibly high standard. He was also paid accordingly, making his relatively short stint in the UFC a highly profitable one.
But if he really is done with the sport, will Lesnar be remembered as a great heavyweight, or simply a memorable one? There's no denying his star-power, but did he accomplish enough to be known as anything more than a lightning rod with incredible athletic ability and raw physical potential?
It's difficult to say, in part because it's hard not to wonder what he might have accomplished had he not been laid low by diverticulitis at the height of his career. Instead of challenging Junior dos Santos earlier this year, Lesnar had to go under the knife to have 12 inches of his colon removed. It might not have had any bearing on his fight with Overeem, but his health struggles almost certainly influenced his decision to hang up the gloves when he did, and deprived him of precious time to carve out more of a fighting legacy for himself.
Lesnar was a man who came to MMA relatively late in life and now seems intent on leaving early. He was memorable, even if he fell short of true athletic greatness, and he brought mainstream attention to the sport at an important time in MMA's evolution.
Maybe when we look back on his brief career, that's what we'll remember most. Not that he dominated or even that he stuck around long enough to find out what he was fully capable of, but that he did a lot in a very little time, and he left the sport in better condition than he found it. Maybe that's enough for him to feel satisfied in retirement. Maybe it has to be. And sure, maybe all the money he made in the process doesn't hurt either.