Age versus grade is just a distraction. Some parents use it as an excuse. It comes down to talent, not age placement in a grade. You either have talent or you don’t.
My son was seventeen on graduation day. There are other poster’s kids on this board in the same boat.
I have a good friend who was in his grade by days as one of the oldest players. He didn’t get to start in school in football and baseball and Legion ball (what we had then) because of all the talent ahead of him. Not all the talent was a class ahead of him. But he had to wait for every senior to graduate. Then, for game experience he PG’ed a year before going to college. He turned twenty early in his freshman year. He still washed out of D1.