Years ago I read an article by Malcolm Gladwell about how children born in January or February do better at hockey than those born in November or December. I found it fascinating and the result is due to the January 1 birthday cut off for youth hockey. Those who were the oldest did better, those who where younger, in general, did not.
Now there's new research that shows the same result for children in Florida with September vs August birthdays. In Florida, the school cut off date for a which grade your child enters is September 1st (and 18 other states). The study found that kids born in September, and thus older for their grade, had a greater likelihood of going to college, while those born in August, had a greater likelihood of being incarcerated for juvenile crime.
I know plenty of parents who have held their children back from entering school if they were on the cusp for their states cut off date. Apparently this was a smart move. Of course these statistics are not absolutes. My daughter has a September birthday, and in New York the cut off date is December 1, and she is thriving. While my son who has a January birthday and is among the oldest in his grade, sometimes struggles.
Like most of parenting, the key is knowing your child. If your child seems less mature than their peers, and is close to the cut off, maybe "red-shirting" might be the solution.