Ok... well, firstly, I mainly chose the positions for the fielders based on the shape of the territories, ie. to get them to fit the territory shape as good as possible... but I think most of them also kinda make sense for their positions. I mean, as much as I understand baseball...

At this point, I personally am pretty happy with all the outfielders + Ozzy & Jackie, so unless there's some significant reason to change them... I mean, they are what, 50 pixels, so I'm not going to try to mimic the actual players because you couldn't recognize them at that size anyway (not even going to the small map...)
I'm not totally satisfied with Mike & Lou though, so if you find any images for them, I'm open to suggestions. The images don't need to be of the actual players, just find images of poses that you think would suit the positions.