My son could have stayed back a year. We decided not to even though he was a "little kid" at 5 years old. We ended up glad we didn't. His class growing up was an amazing group of kids...athletically and otherwise. The grade below him where he could have ended up...not so much. He probably graduated with what overall is probably the most athletic overall class our HS has seen in a long time. 3 D1 athletes (including him)....one each in basketball, football and baseball, which isn't bad from a small essentially rural school with a class of about 70 boys. I would say out of the 70 that probably 55-60 played sports at some point in their 12 years of school. They pushed each other....sometimes probably too much....to get bigger, faster and better. Sure, maybe he'd still have ended up the athlete he was if we'd held him back...but he'd have missed out on a lot by not being in the same class as the kids he graduated with.