I think the thing that will work is baseball specific stuff but the problem is most of our fans don't know baseball. I love when there is a flyball and most of the crowd starts cheering as the outfielder is moving in to catch the ball. Or the PA person plays staying alive when the opposing team fouls a ball off. We have to have a new PA person and music people. They are horrible. No clue about baseball.
But I'm not a fan of cloning football stuff which is what has been tried. It is a different crowd and some of that does not apply. Get a baseball junkie up there to do sound and PA.