My son there when he was 10 I think.
It is a nice place but it is going to be a hard sell turning it into a baseball mecca. The field is literally out in the middle of nowhere in the great cornfields of Iowa. It is great to go see but there is little in Dyersville that will support such a large venue. Dubuque is reasonably close but still a fair drive away.
Good luck to it, it was a fun place to visit.