Its a sad week for the world of mixed martial arts and the UFC. After a career that spanned 17 years, including three UFC championship fights, Chael Sonnen announced his retirement from the sport. The most outspoken and charismatic fighter in UFCs history recently failed a drug test for banned substances leading to his removal from his fight against Vitor Belfort at UFC 175, and rather than wait out another suspension that would push him even further down the ladder of contention, The American Gangster opted to call it a career. The substances in question were allegedly being taken to aid with Sonnens fertility issues, but the legitimacy of that has been questioned. Regardless of the veracity of those claims, and what your views on Chael Sonnen as a fighter and a person may be, the UFC has lost one of their most marketable stars. Whether you were a fan who rooted for Sonnen to win or cheered when he lost, theres no denying that the fighter straight from the mean streets of West Linn, Oregon will be sorely missed. Since his feud with Anderson Silva that began in 2010, Chael has been one of the sports most high-profile competitors, gaining attention and notoriety for his antics outside the cage even more so than his actions inside it. His retirement leaves a huge hole in the UFC, one that will be extremely difficult to fill. In honor of the man who put his mouth to work and his body on the line to provide us with entertainment, lets look at 9 Reasons Why Chael Sonnens Retirement Is A Big Blow To The UFC.