Buentello received the nickname "The Headhunter" due to his propensity, in his early years of martial arts training, to axe kick his opponent's faces.
[3] His third fight was set to be against Gilbert Yvel at Affliction: Trilogy on August 1, 2009, but the entire event was ultimately cancelled due to complications arising from heavyweight Josh Barnett's inability to receive a California State Athletic Commission licence.
Subsequently, Buentello lost to Cheick Kongo on UFC LIVE: Vera vs. Jones where he surprisingly—after a prolonged period of having his legs pounded—he tapped due to elbows to the right thigh in the third round.
[10] Buentello continued his MMA career at the Texas-based Shark Fights promotion, defeating the previously unbeaten (6-0) Bryan Humes via Unanimous Decision.
[12] Buentello was scheduled to face Kerry Schall at Nemesis Fighting: MMA Global Invasion on November 13, 2010[13] but the event was postponed to December 10, 2010 to avoid a tropical storm.
On March 31, 2012, Buentello faced former Shark Fights Heavyweight Champion, and The Ultimate Fighter 10 alumni Darrill Schoonover WMMA 1: McCorkle vs. Heden.
Buentello faced independent prospect Myron Dennis on March 15, 2014, at Legacy FC 29 for their vacant Light heavyweight championship.