The "rule" is a personal preference for some people, i don't see a reasonable way to have a shorter name for what you are trying to represent so i don't think the domain name fails because of length.
However, what is your intended audience? What kind of site would you develop on this domain name? People don't care about Middle School baseball, they care about THEIR school's baseball. A directory? People are not looking for that either, why exclude high schools or other mediums for baseball playing?
I don't think you have any value here, i don't see a good way to develop it.
MY general rule of thumb is that if you can hand register the domain name, it's not worth more than $10 unless you're the end user, or a pioneer in catching trends early.
And not that you asked, but the other domain in your sig (TournamentChampionship), i don't see much value there either. All tournaments end with a champion, that's like having the domain golfballgoesinthehole.com. It doesn't make sense to me.
Good luck!
