Unconventionally gifted kids, who didn't get top grades in high school or who don't have perfect SAT scores, stand a better chance than they do elsewhere of getting in--and of being presented with the highest level of intellectual challenge.
Unconventionally gifted kids do not have any chance of getting a challenge. 
mnli hypothesis: Unconventionally gifted kids do not have any chance of getting a challenge.  premise: Unconventionally gifted kids, who didn't get top grades in high school or who don't have perfect SAT scores, stand a better chance than they do elsewhere of getting in--and of being presented with the highest level of intellectual challenge.