Being a mixed martial arts fighter is quite likely the most difficult occupation in existence. Their daily routine consists of multiple training sessions, each of which involves honing a particular martial arts skill to its highest level, requiring training alongside trained killers. To better learn the finer aspects of kicking a person in the head or the proper way to break a person's arm, one must learn to defend against such things.

Defeat is ordinary and occurs on a daily basis. There is no shame in it, especially in a sport that requires the utmost human courage a person can muster. To be locked in a cage with a lethal martial artist and exchange blows and submission attempts until one party submits, is beaten unconscious, or the referee stops the contest, is an inherently brave act. Most of the "bad blood" between fighters is an act put on to promote pay-per-view sales. These fighters study and analyse their opponents weaknesses to better break them and the mental warfare aspect is almost as important as the physical demands of the sport.

Sometimes, the sport of mixed martial arts celebrates its heroes long beyond their prime. This is dangerous. Evaluating bodies like the UFC's Rankings have an inherent bias based on their ability to promote fights, but routinely shirk their responsibility to protect fighters in decline. They are right to, just as these fighters are right to continue and protect their careers. However, there comes a time in each fighter's career when they are forced to recognize the holes in their game and that improvement is necessary or that it is time to hang it up altogether. These fighters may want to make a similar evaluation.

15 15. Bethe Correia 

For all her talking during the build up to her title fight against Ronda Rousey, Bethe Correia did little to back it up when the Octagon doors closed. Correia suffered her first loss after being thoroughly dominated in only 27 seconds by the most fearsome woman in MMA (at the time). Correia made insinuations about the suicide of Rousey's father and mocked the champion, only to be sent head first into the "Straight Outta Compton" logo on the canvas. This meme-worthy defeat may prompt the Brazilian to go onto achieve great things within the sport, but her credentials remain in question.

14 14. Roy Nelson 

At 39-years-old, Roy Nelson has had a respectable career in the UFC after joining the promotion following an unsuccessful and controversial stint in the short-lived Elite XC. He endeared himself to America with his charm and that big old belly, before knocking out Brendan Schaub on the finale of the Ultimate Fighter: Heavyweights. However, Nelson has lost five of his last six fights against Stipe Miocic, Daniel Cormier, Mark Hunt, Alistair Overeem, and Josh Barnett, who can be considered elite within in the Heavyweight division. Nelson may still be a punishing fighter, but he will probably never be a top 10 fighter again in his career.

13 13. Michael Bisping 

At UFC 100, Dan Henderson connected with a thunderous right hand to the jaw, which sent Michael Bisping to the canvas and his leaping follow up finished one of the most brutal fights in the sports history. Bisping managed to recover phenomenally notching several impressive wins, but always seems to come up short against the true elitoe of the sport like Wanderlei Silva, Vitor Belfort, and current Middleweight Champion Luke Rockhold. His next matchup pits him against Anderson Silva, who is desperately seeking a return to form. Following this last big payday, Bisping should look to pursue a career as a pundit, which has showed promise.

12 12. Anderson Silva 

When Anderson Silva knocked out Rich Franklin to claim the UFC Middleweight Championship in 2007, it was the beginning of his historic run as a UFC champion. In July 2013, that run was brutally ended by Chris Weidman, who caught Silva with his hands down and made him pay the price. The rematch saw one of the most brutal leg breaks in MMA history and likely signaled the end of an era for one of the sport’s all time greatest fighters. Silva's last bout against Nick Diaz was ruled a no contest after Silva tested positive for drostanolone and androsterone. At the age of 40 and considering the UFC's new emphasis on catching PED users, it is hard to believe that The Spider will be able to climb back up the rankings in 2016.

11 11. Gegard Mousasi 

During his last appearance in the UFC octagon against Uriah Hall, Gegard Mousasi was hit by a turning back kick, sent to the canvas with a flying knee, and then beaten with punches until the referee was forced to call for a stoppage. It was a stunning fight, with a decisive ending that left no question as to who was the superior fighter. In spite of this, the UFC currently ranks Mousasi 9th in the Middleweight division, while Hall sits outside the top 10, ranked 11th. Mousasi has a 4-3 record in the UFC and his upcoming test against Thales Leites in February could determine their futures in the UFC's most talent rich division.

10 10. Sarah Kaufman 

Sarah Kaufman entered the UFC at a time when the promotion was desperate to find talented fighters. She was coming off a difficult 2012 loss to Ronda Rousey that ended with a brutal armbar. Her time in the UFC has been a series of challenging and brutal contests that have left her with a 1-2-1 record and she was only saved from a 1-3 record when Jessica Eye tested positive for marijuana. Despite Kaufman's recent losses to Alexis Davis and Valentina Shevchenko, she remains ranked above both fighters in the Women's Bantamweight division.

9 9. Antonio Rogerio Nogueira 

In his last six fights, Antonio Rogerio Nogueira has lost four and his only two victories have come against some of the sport's aging stars, Rashad Evans and Tito Ortiz. His recent battle at UFC 190 with Mauricio "Shogun" Rua was another example of the UFC trotting out aging fighters as part of the undercard for blockbuster fights. Nogueira was in control for a total of 8 seconds during the fight, but he still managed to put up a performance worthy of Fight of the Night honors. Men like Nogueira will never stop fighting on their own accord and organizations like the UFC will continue to exploit this for their gain.

8 8. Quenton "Rampage" Jackson 

After suffering consecutive losses to Jon Jones, Ryan Bader, and Glover Texiera, Quenton "Rampage" Jackson was forced to make a career decision to leave the UFC. He made appearances on Total Nonstop Action Wrestling as part of an agreement with Spike TV and Bellator MMA. Rampage rattled off three consecutive victories, and in his UFC return, earned a decision victory over Fabio Maldonado. While he remains undeniably talented, the UFC ranking Rampage among the Top 10 Light Heavyweights is a bit of a stretch for a fighter who hasn't faced elite competition in the division in almost three years.

7 7. Cub Swanson 

Once considered among the elite fighters in the Featherweight division, the last year has been a rough one for Cub Swanson. After being thoroughly beaten over the course of five rounds at the hands of Frankie Edgar, Swanson was submitted late in the 5th round. Swanson looked completely outmatched during his next fight with Max Holloway and was thoroughly beaten before the Hawaiian sunk in a guillotine choke, forcing Cub to submit. Swanson is now at a career crossroads, sitting firmly outside of the Featherweight Division Top 5 and must win his next fight if he wants to climb back up the rankings.

6 6. Benson Henderson 

Benson Henderson is currently the 13th ranked fighter in the Lightweight and Welterweight divisions according to the UFC. After being handled by the elite fighters in the Lightweight division like Donald Cerrone and Champion Rafael Dos Anjos, Henderson decided to go up to a higher weight class. 2015 saw Henderson's debut at Welterweight, where he won by rear naked choke over Brandon Thatch and had a split-decision victory over Jorge Masvidal. Now, faced with a division of killers like Tyron Woodley, Demian Maia, and Robbie Lawler, it is hard to imagine Henderson climbing back into title contention.

5 5. Paige VanZant 

On December 10th, 2015, at UFC Fight Night Las Vegas, Paige VanZant faced the biggest test of her young mixed martial arts career against Rose Namajunas. During the five round contest, Van Zant was in control for only 33 seconds, while Namajunas landed 57 significant strikes in comparison to Paige's 10. She was taken down eight times and glaring holes were exploited in her defense, while her striking was found to be lacking. Current Strawweight champ, Joanna Jedrzejczyk, is certain the 21-year-old will one day become a champion, but major improvements will be necessary to prevent another beating like this from taking place.

4 4. CB Dollaway 

The UFC's Middleweight division is loaded with talent. From the champion Luke Rockhold through the Top 10, these fighters make up what may currently be the most loaded division in the sport. CB Dollaway has experienced their expertise first hand with consecutive losses to legends like Lyoto Machida and Michael Bisping. However, his most recent loss to Nate Marquardt is cause for concern. Marquardt bucked his losing streak with a vicious right handed knockout. Subsequently, Dollaway has dropped down the rankings and it is unlikely The Doberman will climb back into the Middleweight Top 10.

3 3. Ronda Rousey 

Ronda Rousey is a mixed martial arts legend and one of the sport’s true pioneers. Her judo is unparalleled as far as female competition is concerned in the UFC, but her striking is a severely lacking aspect of her repertoire. Much has been made of the relationship between her and her coach Edmond Tarverdyan, especially because it has remained a glaring weakness and her lack of head movement was thoroughly exploited during her recent defeat at the hands and feet of Holly Holm. Ronda Rousey is the first great female champion in the history of mixed martial arts, but if she wants to continue in the sport, her striking must improve or she will suffer as a result.

2 2. Vitor Belfort 

Vitor Belfort is practically the poster child for the necessity of the UFC's new PED testing policy. For years, Belfort exploited an exemption for testosterone replacement therapy and routinely measured at superhuman levels of the substance, while rattling off first round knockout victories over Michael Bisping, Luke Rockhold, and Dan Henderson in 2013. After an unsuccessful title shot in May 2015 against Chris Weidman, Belfort was unrepentant for his past PED use and claimed to still be using TRT. While his martial arts skills are truly legendary, you can't help but question if these accomplishments haven't been enhanced by his PED use.

1 1. Antonio "Bigfoot" Silva 

Few fighters are as instantly recognizable as Antonio "Bigfoot" Silva. Silva made a name for himself with notable victories over Andrei Arlovski, Fedor Emelianenko, and Alistair Overeem, but in recent years has struggled to find success. He was soundly beaten by Cain Velasquez during their Heavyweight Title bout, had a draw and a loss against Mark Hunt, and was defeated by Frank Mir and Arlovski all within the last three years. At the age of 36, Bigfoot is closing in on retirement and for his own safety may want to consider hanging it up.