Ah, that makes sense. Given what you say about him, it seems that preschool now would be beneficial! We did send both our children at that age -- they enjoyed it and it did seem to help their development. Doesn't seem it would hurt anything (other than the cost, of course!).

BTW, your question got me thinking about this again and I did some searching. This article has some good links.

http://parentsware.com/delaying-kindergarten-facts-academic-redshirting