There are no MMA rankings more speculative yet controversial as the pound-for-pound rankings.
May was a busy month for the world of mixed martial arts and we got to see several interesting, exciting fights that left a noticeable difference in Bleacher Report's rankings.
What are the differences from last month? Who is ranked where? Read and find out!
These rankings are the combined efforts of some of Bleacher Report MMA's best writers as we continue our aim to provide you with the best content on the Web.
Most Recent Fight: TKO victory over Jake Ellenberger at The Ultimate Fighter 15 Finale
Next Fight: Expected to face Johny Hendricks at TBA date
Previous Ranking: N/A
Martin Kampmann's plucky and unexpected victory over Jake Ellenberger has broken him into the top 25 pound-for-pound MMA fighters. Kampmann's blend of aggressive submission attack, footwork and technical kickboxing make him a threat to many.
Most Recent Fight: Split decision win over Josh Koscheck at UFC on FOX 3
Next Fight: Expected to face Martin Kampmann at TBA date
Previous Ranking: N/A
Johny Hendricks has become a hot commodity as of late. He abruptly ended Jon Fitch's long winning streak with a brutal knockout and, more recently, he edged out Josh Koscheck at UFC on FOX 3.
He is one of the best wrestlers at welterweight and packs a mean punch. Such dangerous skills have earned him the 24th spot in the rankings.
Most Recent Fight: Unanimous decision win over Scott Jorgensen at UFC 143
Next Fight: Urijah Faber at UFC 148
Previous Ranking: 21
Renan Barao is one of the most dangerously skilled Brazilians in the UFC—and that's saying quite a bit since there are many tough, admirable, quality Brazilian fighters in the promotion.
Barao is enjoying an unheard-of 28-fight winning streak (not counting the no contest) and is set to face Urijah Faber for the interim UFC bantamweight championship at UFC 148.
Most Recent Fight: Submission victory over Jim Miller at UFC on FOX 3
Next Fight: Winner of Benson Henderson vs. Frankie Edgar at TBD date
Previous Ranking: N/A
Nate Diaz truly came into his own when he smashed Jim Miller at UFC on FOX 3; he was no longer living in his brother's shadow.
Now, all he has to do is wait for Benson Henderson vs. Frankie Edgar to be done, and he'll have a shot at the winner for a chance to be the first Diaz brother to wear UFC gold.
Most Recent Fight: Technical submission loss to Jon Jones at UFC 140
Next Fight: Ryan Bader at UFC on FOX 4
Previous Ranking: 19
Lyoto Machida is a great fighter, but he's seen better days. He's 1-3 in his last four and has a difficult fight coming up at UFC on FOX 4 against a resurgent Ryan Bader.
Most Recent Fight: Draw against Ian McCall at UFC on FX 2
Next Fight: Ian McCall at UFC on FX 3
Previous Ranking: N/A
Demetrious Johnson has been a perennial contender as both a bantamweight and flyweight—a division in which he's currently part of a tournament to crown the very first UFC flyweight champion.
His last fight against Ian McCall—the tournament semifinal—ended in a controversial draw after a tabulation error with the scorecards.
The rematch is set for UFC on FX 3.
Most Recent Fight: Unanimous decision loss to Dan Henderson at UFC 139
Next Fight: TBD. Was supposed to face Thiago Silva at UFC 149 but Silva withdrew due to injury
Previous Ranking: 18
Even though Mauricio "Shogun" Rua lost to Dan Henderson, many considered it a poor decision. However, any ill will over the controversial call didn't last long, since the fight was one of the most incredible in recent memory.
Rua was supposed to face fellow striker Thiago Silva at UFC 149, but Silva withdrew due to injury. It was speculated that Glover Teixeira was to be his opponent, but that hasn't been confirmed.
Most Recent Fight: Draw against Demetrious Johnson at UFC on FX 2
Next Fight: Demetrious Johnson at UFC on FX 3
Previous Ranking: 20
Ian McCall was widely considered to be one of the world's best flyweights. Once the UFC opened their doors to the division, "Uncle Creepy" was given a chance to prove it.
Some believe that he was robbed against Demetrious Johnson at UFC on FX 2, but we'll get to see a rematch at UFC on FX 3.
Record: 10-1-1 (1 NC)
Most Recent Fight: Loss to Frankie Edgar at UFC 136
Next Fight: Clay Guida at UFC on FX 4
Previous Ranking: 14
Gray Maynard seemed nigh invincible, an unstoppable juggernaut, until Frankie Edgar did the incredible and put Maynard's lights out.
Maynard hasn't fought since then but is scheduled to fight Clay Guida at UFC on FX 4 in one of the more intriguing matches of this summer.
Most Recent Fight: TKO Victory over Yasuhiro Urushitani at UFC on FX 2
Next Fight: Winner of Demetrious Johnson vs. Ian McCall at TBD date
Previous Ranking: 13
After failing to get any gold at bantamweight, Joseph Benavidez moved to the newly created UFC flyweight division.
It appears to have been a good choice, as Benavidez is only one win away from the flyweight title.
Most Recent Fight: TKO victory over Antonio "Bigfoot" Silva at UFC 146
Next Fight: TBA.
Previous Ranking: 15
Cain Velasquez came back from his loss to Junior dos Santos a motivated man. He gave Antonio "Bigfoot" Silva the beatdown of his life in one of the bloodiest and most one-sided fights in recent memory.
Most Recent Fight: Submission win over Brian Bowles at UFC 139
Next Fight: Renan Barao at UFC 148
Previous Ranking: 16
Urijah Faber is one of the most talented and notable bantamweights around. He has a great blend of wrestling and striking and a great guillotine to boot.
He was supposed to face hated rival and UFC bantamweight champ Dominick Cruz at the end of The Ultimate Fighter 15, but fate had other plans.
Now, Faber will fight Renan Barao for the UFC interim bantamweight title.
Most Recent Fight: Unanimous decision victory over Josh Thompson at Strikeforce: Barnett vs. Cormier
Next Fight: TBA
Previous Ranking: 13
Gilbert Melendez may not have impressed fans with his decision win over Josh Thompson, but the fact of the matter is that Melendez is still one of the world's greatest lightweights and a force to be reckoned with.
Most Recent Fight: Unanimous decision loss to Jon Jones at UFC 145
Next Fight: TBA
Previous Ranking: 12
Rashad Evans showed mettle in surviving 25 minutes with one of MMA's greatest fighters in Jon Jones and, hopefully for Evans' sake, he can string together some quality wins and earn a rematch with Jones.
Most Recent Fight: Unanimous decision victory over Michael Bisping at UFC on FOX 2
Next Fight: Anderson Silva at UFC 148
Previous Ranking: 11
The "gangster" from West Linn, Oregon, remains static in the rankings at No. 11. When he meets Anderson Silva in an epic rematch at UFC 148, then his true place in the rankings will be known.
Most Recent Fight: Unanimous decision victory over Shogun Rua at UFC 139
Next Fight: Jon Jones at UFC 151
Previous Ranking: 9
Dan Henderson is truly one of the all-time greats and, most recently, he provided one of MMA's most exciting scraps against Mauricio "Shogun" Rua at UFC 139.
For his efforts, he was rewarded with a shot at UFC light heavyweight champion Jon Jones—a fight that will make Henderson into the stuff of legends should he prove victorious.
Most Recent Fight: Unanimous decision victory over Nick Diaz at UFC 143
Next Fight: Expected to face Georges St-Pierre at TBD date
Previous Ranking: 10
Carlos Condit went from a beloved fighter to a controversial one, all because he fought with a brilliant game plan against a fighter with borderline-depraved fans. A fighter with 26 finishes in 28 victories suddenly became a "point-fighter" who "ran away" from the fight.
Regardless of what the detractors think, Carlos Condit is still the UFC interim welterweight champion and is expected to unify his belt with Georges St-Pierre's true UFC welterweight championship when the Canadian is finally healed and ready to fight.
Most Recent Fight: Unanimous decision loss to Benson Henderson at UFC 144
Next Fight: Benson Henderson at UFC 150
Previous Ranking: 8
Poor Frankie Edgar!
After his fight with Benson Henderson at UFC 150, it can be said that he's faced the same three men in his last six fights.
There is some debate about whether Edgar deserves a rematch against Benson Henderson (personally, I thought Henderson had done enough to earn a victory, but can understand giving Edgar a rematch out of courtesy—although I'm loath to see a rematch because it only jams up the division further), but all this talk doesn't change the fact that the match is happening.
Afterwards, we'll know if Edgar is deserving of his top-10 pound-for-pound ranking or not.
Most Recent Fight: Unanimous decision victory over Frankie Edgar at UFC 144
Next Fight: Frankie Edgar at UFC 150
Previous Ranking: 7
According to the judges, Benson Henderson figured out "The Answer" Frankie Edgar.
Nevertheless, the UFC has ordered a rematch between the two men to take place at UFC 150. Should Henderson turn in an even more impressive performance, he will definitely rise in the pound-for-pound rankings.
Most Recent Fight: TKO Victory over Frank Mir at UFC 146
Next Fight: TBA
Previous Ranking: 6
Junior dos Santos proved at UFC 146 just why he's a top-10 pound-for-pound fighter. He has great takedown defense and some of the best boxing and footwork in all of mixed martial arts.
Most Recent Fight: Unanimous decision win over Demetrious Johnson at UFC Live: Cruz vs. Johnson
Next Fight: TBD. Was supposed to fight Urijah Faber at UFC 148 but had to withdraw due to injury
Previous Ranking: 5
Dominick Cruz was primed and ready to face Urijah Faber at the conclusion of this season of The Ultimate Fighter, but the injury curse struck again this year, knocking Cruz out of the fight and forcing an interim bantamweight title to be made.
Still, Cruz is one of the best fighters in the world and his elusive style would give any man trouble.
Most Recent Fight: Defeated Chad Mendes at UFC 142
Next Fight: Erik Koch at UFC 149
Previous Ranking: 4
Jose Aldo's striking is fearsome and his takedown defense is excellent, and he is skilled in Brazilian Jiu-Jitsu to boot!
He has an incredible highlight reel—as any YouTube search will demonstrate—and is most certainly deserving of a spot in the top five pound-for-pound fighters.
Most Recent Fight: Defeated Rashad Evans at UFC 145
Next Fight: Dan Henderson at TBA
Previous Ranking: 3
Despite Jon Jones' recent troubles, none can deny that he's still one of the most incredible fighters to have ever graced the sport of mixed martial arts.
He's dominated seasoned champions as if they were amateurs. Jones has a bright future and will almost certainly top the pound-for-pound rankings one day.
Most Recent Fight: Defeated Jake Shields at UFC 129
Next Fight: Expected to face Carlos Condit at TBA date
Previous Ranking: 2
Not much of an explanation required here. Georges St-Pierre is one of the most dominant champions in the history of MMA and will hopefully return to action against Carlos Condit in the near future.
Most Recent Fight: Defeated Yushin Okami at UFC 134
Next Fight: Chael Sonnen at UFC 148
Previous Ranking: 1
Is there really anyone questioning Anderson Silva's place at the top of the modern-day pound-for-pound rankings anymore?
Silva makes skilled professional fighters and former champions look like rank amateurs who are fighting outside a pub. Few other men who have ever fought in mixed martial arts can boast the same claim.