There is no "perfect" candidate, but there is a perfect mix of candidates. The IWC wants a 60-40 mix of hard science and social science. They like to see prior service but they also value skills and perspectives from the private sector. If the board selects 50 "perfect" candidates with identical backgrounds, the IWC doesn't get the diversity of thought and diversity of expertise it needs to adapt to evolving mission requirements.
That said, the IWC Board does publish its selection criteria and explain how it applies the criteria to select "best fit" candidates. I think it's available online without a CAC... let me look around.
EDIT, found:
https://www.airwarriors.com/community/index.php?threads/fy15-idc-dco-boards.42161/ scroll down to das' post.
I am not sure how much weight is given to the unit OIC confidence rating. Maybe an officer recruiter can shed some light. That said, I am working under the assumption that I won't get selected without a 100% rating. My interview appraisals were 10/10/9, so the 9 worries me.