He might plateau, have an injury, or just have a high school body rather than a college body. There are lots of all star 5’10” short armed offensive linemen wondering why their preferred college won’t take them. Lots of great 6’4” HS power forwards with short arms.

To answer your question more specifically, some few kids show D1 talent early in high school. By that I mean they are already all conference or better as freshman.