I voted no and then saw the thread title "fighter of the year", not "MMA fighter of the year". Overeem has definitely accomplished tons in K-1, much more than I would have expected. I don't know who I would name as the fighter of the year at this point. Will take me a while to think about it.
In boxing, it's clearly Pacquiao (again) this year.
In MMA, there are a few such as Edgar, Velasquez, and Werdum. Although Werdum had one fight this year, he definitely had a bigger win than all the other MMA fighters. Shogun also one but huge win, but he would be after these three imo.
In K-1, it has to be Overeem.
So between all those guys, I'm still undecided