I'm all for the baseball theme, as this is an original appraoch to life poems, and each thing you described kind of did make sense. But there are a few suggestions that I have and I hope you don't mind:
Every boy and every girl.
[This line is okay. It's more of a personal thing but the two every's in one sentence kind of take something from each other.]
Until we come crashing down like a knife.
[Like should seldom be used if used. It works here but I'm not sure about the word knife. I know you need it to rhyme though]
You're happy, sunny day,
[I think you mean your]

Very nice poem. I really liked how you went through and desribed each ball, {Low ball, High ball, Etc.} It was a great poem, With a great meaning to it. The only problem I had was with this line:
"Until we come crashing down like a knife."
It didn't seem to fit in. Great job though. =) 5/5

`Taleee. xx.

Ahh, I like how you compaired life to baseball. Least I think I am grasping that. I hope. Ohwell. I loved it very true aswell.