Back in October 2019, Stipe Miocic was the UFC heavyweight champion. Jon Jones ruled at light heavyweight. Israel Adesanya was the newly crowned king of middleweights. And, well, let's just cut to the chase and say that all 12 of the fight promotion's weight classes had champions who do not reign today.
A lot changes at the top of this sport. A lot changes down the ladder as well. That same month, four years ago, ESPN published our first ranking of the top 25 MMA fighters under age 25. None of those who made the list were champions -- they were young fighters who'd caught the eye of our panelists and appeared to be poised for a bright future. How'd that work out? Some of the fighters in our rankings have since made their mark on the sport -- a couple have even worn championship belts. Some are still climbing toward that and others have experienced more downs than ups.
So, our panel has taken that old list and reranked the fighters. Call this the top 25 MMA fighters who were under age 25 as of the fall of 2019 and now have four more years of experience under their belts. A graduation of sorts for some of the top prospects in the sport -- but who has the best grades?
Editor's note: ESPN's voting panel includes Brett Okamoto, Marc Raimondi, Jeff Wagenheim, Andres Waters, Andrew Feldman and Eddie Maisonet III.
1. Sean O'Malley (17-1, 1 NC)
UFC men's bantamweight champion
2019 Rank: 2
Record since 2019: 7-1, 1 NC
No one in the sport has a higher ceiling when it comes to stardom than O'Malley. The UFC has recognized it, and O'Malley is getting pushed as if he's the second coming of Conor McGregor. While that level of mainstream fame might be impossible to come by, O'Malley is the closest thing the promotion has to Notorious 2.0 after he knocked out Aljamain Sterling to win the bantamweight title at UFC 292 on Aug. 19. The entertainment magazine Variety did a cover story on the TKO merger last week and gracing the cover were WWE champion Roman Reigns and O'Malley.
While O'Malley will be a name the UFC will be riding on at the outset of this new publicly traded company, the question is what will be next for him. It seems pretty clear O'Malley's first title defense will come against rival Marlon "Chito" Vera, the only man to defeat O'Malley in the Octagon. Could that be set up for UFC 300 on a loaded card? Will O'Malley carry his own pay-per-view before or after that? There's no wrong answer necessarily. But regardless of what gets decided, it's abundantly clear O'Malley is the UFC's new "guy." -- Raimondi
2. Umar Nurmagomedov (16-0)
UFC men's bantamweight
2019 Rank: 19
Record since 2019: 4-0
There is no ceiling on Nurmagomedov's talent. He's still only 27, and it looks like he'd be ready to hold a championship right now if given the opportunity.
Like his retired cousin, Khabib, he's somehow managed to stay perfect in a sport rife with potential pitfalls. The UFC has bought into Nurmagomedov's potential and is more than willing to give him a big fight. He was booked to fight Cory Sandhagen in August before a shoulder injury forced him to withdraw. Before that, the UFC discussed pairing him against Merab Dvalishvili. He's expected to return in the first quarter of 2024 and go into the year as one of -- if not the -- marquee names to watch. His game is balanced and well-rounded. He's a far more dangerous striker than Khabib, and he carries the Dagestani wrestling pedigree to go along with it. His next fight will be a big one, and you can bet the UFC will put it in a showcase spot to build his name. -- Okamoto
3. AJ McKee (20-1)
ESPN's No. 5 ranked featherweight
2019 Rank: 1
Record since 2019: 5-1
McKee was No. 1 in our 2019 rankings because he appeared closer to gold than any other young fighter. He had just won his opening bout in the Bellator Featherweight World Grand Prix by knockout -- in 8 seconds. How'd he justify his rankings? McKee breezed through the rest of the tournament, finishing everyone in his way. That included fellow finalist Patricio "Pitbull" Freire, who also held the Bellator title at the time of their 2021 bout. So winning the tourney didn't just earn McKee a shot at the championship. It made him the champ. McKee lost the belt to Pitbull in a rematch last year. That set McKee's eye on a new frontier: the lightweight division. He won two fights at 155 pounds to earn a spot in the Lightweight World Grand Prix, where in the first round, he would face another Freire -- Patricio's brother, Patricky, a former champ. But an injury scuttled that July fight and McKee's participation in the tourney. To begin the road back to opportunity, he will take on Sidney Outlaw at Bellator 301 on Nov. 17. -- Wagenheim
4. Arman Tsarukyan (20-3)
ESPN's No. 9 ranked lightweight
2019 Rank: 25
Record since 2019: 6-1
This may be a bit of hyperbole, but few things outside the Octagon are more difficult in MMA than finding an opponent for Tsarukyan. The UFC and Tsarukyan's manager, Daniel Rubenstein, have their work cut out for them. Tsarukyan is a guy who made his UFC debut against Islam Makhachev of all people and made Makhachev, now the UFC lightweight champion, work for every position in a close decision. With his dominant wrestling and grappling and budding power, Tsarukyan is a nightmare matchup for anyone at 155 pounds. He has legitimate championship potential.
Tsarukyan doesn't have a fight booked right now, but he's sitting at No. 9 in ESPN's divisional rankings and should be looking at a big fight next. He's probably one or two wins away from a title shot. But in Tsarukyan's case, that could take a year because there aren't many takers to get into the Octagon with the guy. Hopefully, things open up and we get to see him show his skills against the best fighters in the division soon enough. --Raimondi
5. Song Yadong (20-7-1)
UFC men's bantamweight
2019 Rank: 8
Record since 2019: 5-2-1
Somehow, Song is still a few months away from his 26th birthday, yet he has nearly 30 professional fights under his belt -- including 12 in the UFC. That is a wealth of experience for his age, which should complement his growing skillset and physical maturity nicely in the coming years. Whereas his counterpart in the top-5 of this list, Nurmagomedov, is widely viewed as a future champion, Song isn't quite on that level. He's still a wait-and-see prospect. Does he have the ability to truly give the very best of this division a run for its money? Last year, he fought Sandhagen evenly through four rounds before the fight was called off due to a cut. The fact he was able to fight evenly with Sandhagen through 20 minutes shows how good this Chinese contender is, but it was still a loss. He's considered a threat at 135, but a bonafide future champ? We'll still have to see. -- Okamoto
6. Aaron Pico (12-4)
Bellator featherweight
2019 Rank: 13
Record since 2019: 8-1
There are young fighters and then there are young fighters. When Bellator signed Pico in 2014, he was 17 years old. "Simply put, Aaron has all the makings of MMA's next great superstar," company president Scott Coker gushed, "and to have him here at Bellator MMA is something special." Pico was a two-time medalist at the World Junior Wrestling Championships and would later just miss out on making the U.S. Olympic team. He did not make his pro MMA debut until 2017 -- and lost via submission in just 24 seconds. The hype train was derailed. There have been other bumps in the road, but ever since suffering two knockout losses in 2019, Pico has won eight of nine and is on the verge of challenging for the featherweight title. -- Wagenheim
7. Jalin Turner (13-7)
UFC lightweight
2019 Rank: 21
Record since 2019: 5-2
In terms of pure in-cage potential, Turner's ceiling is as high as anyone's on this list. He's still just 28 years old. At 6-foot-3 with a 72-inch reach, Turner is a difficult stylistic matchup for anyone in the UFC lightweight division. He's shown power as a striker, along with durability and composure against top fighters. Turner has lost two straight but consider the circumstances. Both were split decisions he absolutely could have won. And losing to Dan Hooker and Mateusz Gamrot is nothing to be ashamed about. Turner very well could be fighting for a UFC championship one day. --Raimondi
8. Maycee Barber (13-2)
UFC women's flyweight
2019 Rank: 6
Record since 2019: 5-2
For a minute, this train was going off the rails back in 2021. Barber hit her first road bump in 2020, when she suffered her first loss to Roxanne Modafferi and a torn ACL. After nearly two years off, she returned and lost to Alexa Grasso, who was only 3-3 in her last six fights going into that matchup. She was not the Grasso we've come to know today as the UFC's flyweight champ. And then immediately after that, Barber went on to barely squeak out a split decision over Miranda Maverick, in a fight many thought she lost.
All of those hardships considerably cooled any hype around Barber's title aspirations. In the time since, however, Barber has found her stride. She has won five in a row, including an impressive showing against Amanda Ribas in June, despite being a significant underdog. -- Okamoto
9. Christian Lee (17-4)
One Championship lightweight and welterweight
2019 Rank: 22
Record since 2019: 4-1
It's easy for fans in the United States to overlook the Singapore-based One Championship, which only recently began airing its fights on American TV. But Lee's accomplishments are attention-grabbing. At the time of our 2019 ranking, Lee had just knocked out the veteran star Shinya Aoki to win the One lightweight championship. Since then, he has lost the title and won it back. And last November, Lee added the welterweight title as well. Christian and his atomweight sister, Angela, are the only siblings in MMA to reign as champs. -- Wagenheim
10. Angela Lee (11-3)
One Championship women's atomweight champion
2019 Rank: 14
Record since 2019: 1-1
Life outside the cage has been extremely hard for Lee. Her sister Victoria, also a fighter for One Championship, committed suicide last December. Lee has not fought since October 2022 and might never fight again, but what she has done cannot be overstated. She won the One women's 115-pound title at 19, making her the youngest major MMA champion ever. Lee defended that title five times and was never defeated for it. She's been one of the main faces for One for nearly a decade and yet is only 27 years old. If she does step away, she should be proud of everything she was able to accomplish. --Raimondi
11. Jack Shore (17-1)
UFC men's bantamweight
2019 Rank: 16
Record since 2019: 5-1
Representing the country of Wales, Shore is the region's best hope at the moment to claim a UFC championship. Shore, 28, had a big opportunity to thrust himself into title conversation when he fought Ricky Simon in July 2022 but came up short in a submission loss. That result was disappointing, but Simon is a dark horse at 145 -- in other words, a loss to Simon doesn't mean Shore isn't capable of making a run in this division. Shore is skilled and quietly 6-1 in the UFC. He will get some high-profile chances in 2024, and if he makes the most of them, he'll make more noise in the UFC's standings than most. -- Okamoto
12. Nasrat Haqparast (15-5)
UFC lightweight
2019 Rank: 4 (tied with Aspen Ladd)
Record since 2019: 4-3
Haqparast was 11-2 and four fights into his UFC career at the time of our 2019 ranking. He had a rough go of it for a while, dropping three of his next five bouts and pulling out of a couple because of injuries. But now the German-born lightweight has won two in a row and is again headed in the right direction. -- Wagenheim
13. Edmen Shahbazyan (12-4)
UFC middleweight
2019 Rank: 3
Record since 2019: 1-4
Shahbazyan won his first four UFC fights dominantly in 2018 and 2019, the last three via finish. He looked like a potential future UFC middleweight champion. Then the competition got steeper and some of the holes in Shahbazyan's game were exposed, namely cardio and defensive wrestling. Since the hot start, he has lost four of five. Shahbazyan is still just 25 years old and recently changed camps to Xtreme Couture. There is still hope for him. -- Raimondi
14. Thiago Moises (17-7)
UFC lightweight
2019 Rank: 20
Record since 2019: 5-3
It doesn't feel like Moises is only 28 years old, and that's because of the level of competition that he has faced. He has been thrown to the absolute wolves during his time in the UFC. The obvious names he's fought include Islam Makhachev and Beneil Dariush -- and if the list stopped there, you'd already say he's had tough matchmaking in the UFC. But then you add Damir Ismagulov, Joel Alvarez and Benoit Saint-Denis. Some of these names are less well-known, but these are established fighters with records or high-ceiling guys with great talent. And that's not even to mention some of the veterans he's gone up against in Bobby Green and Michael Johnson. If Moises has been "disappointing," it's only fair to consider who he's fought. Don't be surprised if he suddenly finds his stride and starts stringing together wins. Despite the up-and-down record, he has talent. -- Okamoto
15. Aspen Ladd (11-4)
PFL women's featherweight
2019 Rank: 4 (tied with Nasrat Haqparast)
Record since 2019: 2-3
When our 2019 rankings were being compiled, Ladd had just suffered her first career loss. But it had come to a former UFC champion, Germaine de Randamie, so Ladd's stock did not immediately plummet. However, Ladd then lost two of three bantamweight bouts in the UFC and had fights canceled because of injury, illness and weigh-in problems. She was released by the UFC, picked up by the PFL before this season and missed the playoffs. -- Wagenheim
The rest of the 2019 25 under 25 class
Gillian Robertson gets back in the win column with a submission win over Priscila Cachoeira at UFC 269.
16. Gillian Robertson (12-8)
UFC strawweight
2019 Rank: 12
Record since 2019: 5-4
17. Michal Oleksiejczuk (19-6)
UFC light heavyweight
2019 Rank: 11
Record since 2019: 5-3
18. James Gallagher (12-2)
Bellator featherweight
2019 Rank: 9
Record since 2019: 2-1
19. Jimmy Crute (12-4-1)
UFC light heavyweight
2019 Rank: 7
Record since 2019: 2-3-1
20. Ricardo Ramos (16-5)
UFC featherweight
2019 Rank: 10
Record since 2019: 2-3
21. Montana De La Rosa (12-8-1)
UFC women's flyweight
2019 Rank: 17
Record since 2019: 2-3-1
22. Sabina Mazo (17-1)
LFA women's flyweight champion
2019 Rank: 23
Record since 2019: 3-3
23. Pedro Carvalho (13-8)
Bellator featherweight
2019 Rank: 18
Record since 2019: 2-5
24. Sage Northcutt (12-3)
ONE lightweight
2019 Rank: 24
Record since 2019: 1-0
25. Ismail Naurdiev (19-5)
Brave CF welterweight
2019 Rank: 15
Record since 2019: 0-2