No they do not explain non-select. I was also surprised you were not picked up. When you resubmit, suggest you pursue 3 or more LORs from Officers O-4 and above. You had a higher GPA/much higher ASTB & OAR, than one ProRec-Y I checked, but one big difference was his 3 militaryO LORs. Don't know if that's it or not, but it kind of stood out when I compared the posted package info. Also, think back if there were any leadership experience(s) you may not have documented which would help. PM me if you have any questions... just start improving your package to resubmit. I know it's frustrating, but
DON'T GIVE UP!
BzB