Phil Davis won over Lyoto Machida at UFC 163 in a result UFC president Dana White questioned. Twitter was filled outrage over the decision in the fight. MMA as we know it is a young and growing sport, so judging will improve as the sport gets older right?
Not necessarily. Judged sports have been grappling with the problem of judging for years, and they're still messing it up.
In 2004, the Olympic men's all-around gymnastics competition was marred by controversy after the score of South Korean Yang Tae Young's parallel bars routine was incorrectly tabulated. Because the error was not noticed in time, American Paul Hamm still won the gold while Young won bronze.
The Winter Olympics in 2002 also had a judging controversy. In figure skating, two gold medals were awarded in the pairs competition after a judge admitted she ranked a Russian pair over the Canadian pair because she was pressured to do so.
MMA is judged like gymnastics and figure skating, but fighters have the advantage that they can win a fight without judges' involvement. This makes it more like wrestling, which had a judging controversy in the 2008 Olympics.
Swedish wrestler Ara Abrahamian had his score changed in what he deemed as an arbitrary manner. He protested, but the referees refused to review his match. Abrahamian went on to win the bronze, but threw the medal away during the ceremony.
Like in every judged sport, MMA judging is done by humans who don't all see everything the same way. There will be disagreement not just because humans are doing the judging, but also because they are judging two humans fighting each other. It doesn't get much more subjective than that.