Most of the families in my social circle who redshirt would be in that category as well. Unfortunately for their purposes, most competitive team sports have strict age ranges, (typically August 1st cutoff) which allow playing up, but not redshirting, which kick in around grade three.
It is true that kids who just miss the cutoff, and thus are nearly a year older than their peers, tend to be favored athletically, apparently because the perception of superior skill which is created by the purely chronological difference in physical development, leads to access to additional playing time and coaching support, which creates a cycle of compounding skill advancement compared to children who just make the cutoff, and are thus young for athletic grade. Surveys of professional athletes have found greater than chance bias toward fall birthdays.
