From my experience the sponsored cadets ranged in their background quite a bit and were not neccesarily mathematical geniuses, but seemed to be fairly well rounded and generally competent. I think that there is a bit of luck involved in the selection process and not getting selected does not mean that you will not necessarily do better at the flying training than someone who did get a place. There may be a better pass rate for sponsored vs non-sponsored but sponsored guys werent any better than good self-sponsored students. In fact, I think paying the bill yourself makes you more dedicated and you would have a tendency to work harder as its your money on the line.