Chandlers breakout year was this year IMO. My vote goes to stipe Miocic. In the UFC, is a hw, and will be pumped by the UFC hype machine. As long as he wins, this will be your breakout fighter for 2012 IMHO 
Weidman... Training under Renzo, the guy is transforming each time you see him. His bjj looked good in his last fight.
Chris Weidman, Costa Philippou, Ian McCall, Carlos Condit.
DoubleBACO -ghostmaster -bonersaurus - Bendo, Cerrone, Macdonald, and Condit. <img src="/images/phone/apple.png" alt="Phone Post" border="0" style="vertical-align:middle;"/>My list exactly <img src="/images/phone/apple.png" alt="Phone Post" border="0" style="vertical-align:middle;"/>
Bendo and Cerrone both ? If they have breakout years they will run into eachother by the end of the year, so the winner would have the breakout year. I think speculating on breakout fighters only allows 1 per weight class,,unless there is a large enough gap between the skillset of these fighters, or different org.
Yeah ok I want to see Bendo and cerrone again and hope cerrone comes out on top
Rory Mac and Nick/Nate Diaz
Flyweight - Dodson
Bantamweight - McDonald
Featherweight - Pearson
Lightweight - Pettis
Welterweight - McDonald
Middleweight - Weidman
Lightheavyweight - King Mo
Heavyweight - Cormier
By breakthrough I mean into division top 5.
Not sure who will be the breakout star since there are so many, but my top 5 are:
Cormier
Bendo
Rory MacDonald
Phil Davis
Ellenberger
Notable Mention
Palhares will end up having a huge cult following if he continues his weird episodes.
Michael McDonald.
Gegard will continue to evolve and make a splash in LHW or maybe even MW.
Edson Barbosa.
Luke Rockhold and Ian McCall
Alex Caceres
I think the biggest breakout fighter of this year will be Renan Barao, I think he'll finish Scott violently and then dethrone Cruz (or Faber I guess)
Alan Ma'fuckin Belcher
Benson Fo'Sho
Cerrone and Ellenberger will be big names that the average fan doesn't know but will know by December 2012.
Cerrone may hold the LW title, Ellenberger may hold the interim WW title.
Uncle Creepy: Ian "The Cat" McCall
Crooklyn - Erick Silva
El creepo it is. 
Paul Harris