So, why are you considering holding your 11U kid back?
1. Youngest in his class;
2. Maturity level in young men in general; and
3. Smaller frame child from smaller frame parents.
If you were in our school system you would be laughed out of the building if you attempted to hold your child back for sports reasons. if you were really worried about his age/maturity you would have started him in K/1st grade later. Let's not pretend your on a baseball website asking about NCAA rules for an 11 yr old for any reason other than holding him back in hopes he can have one more yr to develop.
Crazy idea.
by the way, your son can burn out in a few yrs and not want to play anymore, I see it all the time. Be prepared in case it happens. Please find something more productive to do with your time then considering messing with your child's education over sports.
I would have to agree with playball2011. I read 4seamers response on the other thread about when to showcase. Please take a breadth and relax. you have a lot of time before you should be worrying about your sons college baseball future.