I see redshirting in NJ for summer birthdays. They have an Oct 1st cut-off for K so people redshirt earlier. I think redshirting is dependent on the K cut-off. Hence you have a kid with a fall birthday, like mine in a place where redshirting is not allowed, NYC) who will be going to college with kids sometimes 2 years older. I think there is a significant sexual maturity difference between a 19 year old and a 16 year old, even though both are freshman in college.

Ren