Yeah... I have no idea how the Board will really work, although my mentor served on a past IDC Board and told me about it.
From all the RUMINT that I've gathered, I just imagine a massive conference table in Tennessee with two stacks of resumes. One stack is candidates who received 100% confidence, the other stack is candidates whose packages reflect somewhere less than 100% confidence. From the 100% stack, the Board then selects the top candidate out of each NRD for Intel. That's 26 people. Maybe one or two NRDs don't get a single candidate selected -- but I doubt it's too lopsided, because at the end of the day they need each region to be adequately manned. Then, maybe the Board selects 10-15 other outstanding Intel applicants. They'll select 5-10 total candidates combined for IW/IP/METOC, based on need.
Like any organization, they are reconciling talent supply & demand to meet the needs of the organization. Here, there's a huge supply of talent. Very limited demand.
My SWAG is: It's a whole person look, and it's a best fit concept. I submitted for Intel designator only. I reckon if I'm not 100% certain which Navy career field I want to join, then I am not ready for a commission. The career fields of IW and IP exhibit more functional overlap, though, so maybe it's less of a constraint to submit for both of those designators.
Again, take my words with a brick of salt. I may be way off base.