Dhoni is currently the no. 1 ranked one-day player. He has been consistent in one-dayers for a while. Maybe Indian guppies can enlighten us on this. These nominations take into account individual brilliance + consistency over the past year regardless of whether or not you won anything for your country. That ofcourse does not completely rule out bias.
And I agree Afridi should have been there but maybe the ICC regards T20 as a lesser form than ODI. Not so sure about Onions though