Not uncommon for a senior high school football player, especially depending on how his birthday falls. Parents will hold back a kid one year to allow for physical (not mental as in this case) maturation as a player.
Yep, they hold them back here, too, at taxpayers expense. So your Johnny can be bigger than my Tommy on the ball field. We didn’t hold ours back. One graduated at 17. Believe it’s our job to teach kids how fly, not make life easy for them. That’s why we’re in the current mess.