Frank Mir rivalry

In 2003, Sims fought a controversial fight against Frank Mir at UFC 43. At the very beginning of the fight, Mir put out his hand to touch gloves and Sims rushed past Mir's outstretched hand and into a quickly maneuvered takedown by Mir. In the first round, after slamming Mir to prevent an armbar, Sims got up while Mir was on his back against the fence and proceeded to stomp Mir's face several times while holding the fence for extra balance. The fight was stopped and Sims was disqualified.

This started a rivalry between the two and they met again in 2004 at UFC 46. Mir easily took control of the first round with an arm triangle attempt. Near the end of the second round Mir hit Sims with knee strikes to the face and then punches to knock Sims out.

Mike Kyle bite incident

Sims fought again in the UFC at the UFC 47 against Mike Kyle. Sims took the fight on less than a weeks notice after Kyle's original opponent got injured. Kyle dominated the entire first round and knocked Sims out at 4:59. Sims protested after the fight that Kyle had bitten him on the chest.^[3] During the post fight interview, a bite mark could clearly be seen on Sims' left pectoral muscle. This marks the first time a bite has ever happened in a UFC fight since its UFC 1 in 1993, when Gerard Gordeau bit Royce Gracie in the championship match. When asked in the cage after the fight to explain the bite, Kyle told commentator Joe Rogan "he's a dirty bastard anyways, look at all the stuff he's done..." Kyle denied any wrongdoing.

After losing to Kyle he was released by the UFC.

Tim Sylvia rivalry

Wes Sims faced former UFC heavyweight champion Tim Sylvia at SuperBrawl 38. Sylvia was coming off a title loss against Frank Mir, a fight in which he broke his right arm and needed a titanium plate inserted. The two did not touch gloves and Wes began the fight by sprinting towards Sylvia and then backing away. Sylvia got a takedown early and passed through to mount almost right away, but accidentally mounted his knee on top of Sims' shoulder, seriously injuring it. Wes was unable to defend himself with the injury and Sylvia won by strikes in the first round. Tim and Wes had a heated exchange after the fight when Sylvia called Sims out and said he did not deserve to stand in front of him. Wes ran up to Sylvia and trainers had to separate the two. Wes and Tim were supposed to have their rematch for the International Fighting Championships (IFC) Heavyweight title June 6 but Sylvia was injured and the fight was cancelled.^[4]

The Ultimate Fighter

Sims returned to the UFC as a cast member on the tenth season of The Ultimate Fighter, which began filming in June 2009.^[5] Sims was defeated by castmate Justin Wren via arm triangle in the first round of Sims' first fight in the house. Despite his early exit from the competition, Sims was seen regularly on the show and may have earned a reputation for being one of the bullies of the household due to his constant childlike taunting of Matt Mitrione and Zak Jensen.

Strikeforce

Sims made his Strikeforce debut against Bobby Lashley on January 30, 2010, at Strikeforce: Miami.^[6] Sims came up short and was defeated by Bobby Lashley by TKO. Sims was taken down at the beginning of the first round by the decorated wrestler, who then used the ground and pound technique on the 6'8 UFC veteran. The referee stopped to the fight much to the dismay of Sims, who believed that the stoppage was premature. Sims was expected to fight former UFC Heavyweight Champion Tim Sylvia in Ohio outside of Strikeforce but the Ohio State Athletic Commission did not sanction the bout, citing that the fight was "non-competitive".^[7]

Mixed martial arts exhibition record