What does beisbolista mean? If you looked it up in a Spanish to English dictionary, you'd find this simple translation:
beisbolista mf baseball player
(Those of you who took Spanish 1 in high school are probably thinking, "whoa, I seem to remember something about an -a ending on a word indicating that it's a girl, or something like that...," but you're just going to have to trust me on this, it's beisbolista for a man or a woman.)
Now while this is the technical translation, in most Spanish-speaking countries, beisbolero is the more widely accepted term for a baseball player (or baseballer), and pelotero is used as a general term for a ball player (or baller, hee hee).
Here's where it gets interesting. Since beisbolista is so rarely used to describe a baseball player, I've decided to hijack it and give it my own meaning. (Please forgive me if your Spanish-speaking region is one of the places where it is used.) Following is the translation from the Sarah-bug to English dictionary (on bookshelves soon):
beisbolista mf 1 (aficionado) baseball lover, baseball fan
2 (articulista, escritor) one who blogs about baseball; ella es una ~ loca she is a crazy baseball blogger
Hope that clears things up for you. If you need further explanation (or disagree with anything I've said), please don't hesitate to comment.