We held my son back and while it wasn't uncommon then, it is uncommon not to now. My oldest was born late August, would have been the youngest, or we hold him and he is one of the oldest. Preschool teacher said he wasn't emotionally ready and we knew he would be a late bloomer. A week before turning 13, he was 5' flat. At 14, he was 5'8 and ended up graduating at 6'3 and 205 . It 100% made a difference in his ability to reach his goals. Our youngest son is 5'3 and almost 13. He will likely be bigger than his older brother and he is 8-12 inches shorter than almost every kid on his 7th grade football team. Every boy he knows in his grade is almost a full year older. He was born in February...couldn't justify it. That said, there are many kids born around the same time that are a grade below. I see the value in holding them. I don't blame anyone. Reclassifying in high school usually only makes sense if the kid really hasn't developed physically yet, but this year and last...who knows.