I think dark amber, copper or brown colors of sunglasses are suitable for baseball and other sports. These colors can block much blue light which may cause damage to our eyes. So selecting theses colors of sunglasses can not only protect your eyes but also enhance the contrast and visual acuity.
For baseball player, you need colors that can block much blue light in order to enhance contrast and visual acuity, especially the contrast to grass and blue skies. So copper or brown colors are suitable for you.