It's not rocket science, all of these guys getting picked up have posted their stats. Do you have a masters in a relevant field? Do you speak a critical language? Have you interned/worked in the IC? Do you have flag officer LORs? Give your recruiter or the detailer a call and they should pick up pretty quickly on where you are lacking...
Excellent point, the great thing about this site is that there are so many applicants on here. We all get a great snap shot of what the board is looking for. It is not written in stone but by doing a little searching through the profile and posts of those selected you can see what they had that you may not have had if you were not Pro-recd.
I see a lot of people say "well I had a great GPA" or "my OAR was amazing". The board is looking for what we call a "break out", what sets you apart from everyone else applying. The areas you mention...masters, critical language, etc. mean a lot when the board has to decide between two folks with great OAR's and GPA's.
You have to throw something out there that no one else is going to have. For example, for the SWO board I submitted my Coast Guard Captains License. I highly doubt anyone had he same thing but it shows my understanding of nautical rules.