I agree that high school GPA and ACT are not perfect measures, and people often defy the statistics. But High School GPA and ACT/SAT have been shown time and time again to be the best indicators of college performance. I don't know what else a school should use to determine who to accept or not, even with athletes.
The anomalous student who under-performs in high school should do what you did. Go prove yourself.
I don't know what this has to do with football. . . .