5-year-old player

I haven't read a single response in this thread - yet. I'll probably skim them after posting mine.

What is his league age (i.e., is his birthday on or before July 31 - if so, he is considered 6 this year; depending on the league he plays in, the cutoff date may be changed to April 30 next year)?

Not a lot to go on, but from what you are saying, I'd suggest looking into playing up with older kids. Around here, kid pitch starts at 8 in the recreational league. From the sounds of things, he could play successfully in that league next year. It helps if he is big for his age, but by no means is it required (not the size of the dog in the fight but the size of the fight in the dog).

If he continues to progress, playing up has great advantages. By playing up he probably will not be the super-stud. As long as he is firmly in the top 6 or better, great. That, and as long as he has a manager/coaches that can look past the age difference.

By playing up, he should be looked upon as the ace pitcher that the coach rides 95% of the time. By playing up he can face better competiton locally without having to travel all across the city/state/country. Since that challenge can be found locally facing older players, he may also not have to play lots of games that the "elite" teams his age might consider necessary to find remotely similar competition.

If playing up doesnt work out, he can always play back at his age. If you have the positive attitude and all of you can face challenges well, even if he's overmatched you should be able to get a positive experience.

Educate yourelf about pitch counts, rest periods, types of pitches, etc. Look into the book "A Parent's Guide to Pitching". Attend a local baseball camp or get a lesson or two if you don't feel confident in teaching the basics (not really necessary - even if you don't know the basics, get a book like the one I suggested, rent some tapes, watch some "typical" pro pitchers on TV). You do not need any more preparation than that for now.