Well lets take a look at the five fighters in 2012 on the list:
Demetrious Johnson (2-0-1): Mighty mouse had 3 very close decisions including one draw. He proved he was the best at 125 but didn't showcase anything spectacular or dominant. No way did he deserve FOTY.
Cain Velasquez (2-0): Mr. Velasquez had two incredibly dominant wins but one was against a highly overrated Antonio Silva. Definitely more deserving than mighty mouse but still only one real win against an elite HW. IMO, has all the momentum in the world of becoming the FOTY in 2013 but definitely deserved to fall a little short in 2012.
Jon Jones (2-0): Bone's proved once again why he's the best in the business at 205 last year but no way deserving of FOTY. A boring lackluster win against Rashad and a near defeat against a true 185 lb'er shouldn't win you any awards.
Anderson Silva (2-0): This mother ****er proved me and a bunch of others wrong by defeating Chael Sonnen in IMPRESSIVE fashion in the rematch then went on to face and brutally defeat one of the biggest light heavyweights in the UFC in typical spider fashion. Only reason why I see Bendo edging Silva out is because of Bonnar's ranking at 205.
Ben Henderson (3-0): Whether controversial or not, Bendo took the belt and defended the belt against the best and baddest 155 lb'er on the planet then went on to CRUSH the top contender who was running through people in one of the most dominant five round performances I can think of.
It's a little disrepectful not to give FOTY to Silva considering he's never received the award but its also hard not to give it to Bendo here.