kindergarten redshirt
When a parent (usually the father) will hold back their child from starting kindergarten for a year solely for the belief that an extra year of physical development will pay off athletically once the child is in high school ten years later.
That kid is in 1st grade but he should be in 9nd. He is a kindergarten redshirt as his dad thinks he will be a big football star in high school with that extra year to grow.