By the time Saturday's UFC 293 concluded, Sean Strickland felt like he was dreaming—and not as most fans expected — because he had been knocked out by middleweight legend Israel Adesanya.

Instead, the American pulled off one of the biggest upsets in modern UFC history, out-striking the former kickboxer Adesanya for five rounds to win a unanimous decision and the promotion's coveted middleweight belt.

"Am I [expletive] dreaming?" a teary-eyed Strickland said in his post-fight interview with commentator Daniel Cormier. "Am I going to wake up?"

"Never in a million years did I think I would be here."

UFC @ufc

.<a href="">@SStricklandMMA</a> at a loss for words after becoming the undisputed champ 👏 <a href="">#UFC293</a> <a href="">

Strickland will have plenty of time to come to grips with his shocking championship win on the long flight home from Sydney, Australia. Adesanya, meanwhile, will soon board a flight south to his adopted home of Auckland, New Zealand, and will surely be doing plenty of his own thinking at cruising altitude.

The former champion, who is considered one of the greatest fighters in MMA history, simply didn't look like himself in the Octagon and he, like the rest of us, is likely wondering why.

The main catalyst for Adesanya's loss, of course, was Strickland's fantastic yet remarkably simple game plan. The American, who was thought to have a solid grappling advantage in the matchup, did not shoot for a single takedown and instead beat the champion up with a rudimentary boxing attack for 25 grueling minutes.

ESPN MMA @espnmma

SEAN STRICKLAND APPLIED THE PRESSURE 💥 <a href="">#UFC293</a> <a href="">

Yet it's very possible there was another factor at play.

Adesanya's flamboyant persona and flashy fighting style make it easy to forget that he is already 34. That's around the age that many fighters begin to show signs of decline—oftentimes very abruptly—and Adesanya could be at greater risk of a quick fall from the mountaintop than the majority of his peers.

The former champion has now fought 27 times in MMA, with 23 victories and three losses. He has only been knocked out in one of those bouts—a 2022 loss to Alex Pereira—but has taken some punishment in others, most notably his 2019 interim title win over Kelvin Gastelum, which saw him absorb 91 strikes over their five-round war.

Not only has Adesanya had his share of tough fights in MMA, but he has also kept an absurdly busy schedule for the bulk of his career. Since joining the UFC in February 2018, he has fought 16 times. That works out to a fight roughly every four months, which is a lot for any fighter, let alone one like Adesanya, who has been battling world-class talent the entire time he's been in the Octagon.

And of course, Adesanya's MMA career didn't begin in the UFC. He had 11 fights, all wins before he even stepped foot in the Octagon. Those victories occurred over a much more reasonable period of six years, but that's because he was also competing as a kickboxer and boxer in that span.

By the time he had committed to MMA full-time, he had competed 80 times in the kickboxing ring, and six times as a boxer. That brings his total number of pro fights to 113—and that's ignoring the countless hours he has spent sparring with the likes of Carlos Ulberg, Dan Hooker and Brad Riddell at City Kickboxing in Auckland

Adesanya has simply had a far longer career than your average 34-year-old fighter, and it was quite possible he finally started showing signs of his mileage at UFC 293, when he looked far slower and less coordinated than we're used to. He was badly hurt by a first-round punch from Strickland, who has never been known for his stopping power.

Of course, there are other explanations for Adesanya's UFC 293 loss. Perhaps Strickland simply has his number, the way Frankie Edgar had BJ Penn's or TJ Dillashaw had Renan Barao's. Or maybe the former champ took his challenger lightly—he did talk a lot about being levels above Strickland in the lead-up to their fight.

For better or for worse, we should get a much clearer picture of his future in his next few fights, which will make it very interesting to see what the UFC decides to do with him. A rematch with Strickland is possible and something Dana White hinted at in his post-card press conference. He could also be booked for a rematch with a fellow former champ Robert Whittaker, whom he has beaten twice, or for a fight with Dricus Du Plessis, who is the most heated rival in the division at the moment.

Whomever he is matched up with next, however, his fans would be wise to get used to the unfamiliar feeling of seeing him outclassed by fighters he most likely would have dominated a few years ago. Unfortunately, it may not be long before it happens again.