There are several factors make him wearing goggles, and he wears goggles to protect himself for sure, it's pretty dangerous to play baseball as a professional player. And I heard about that he has near sightedness. He can't wear glasses when he is in a game, and contact lenses can be a little bit dangerous to him, so he choose to wear goggles with prescription.
By the way, he is not the only one who like to wear goggles, lots of professional sports player wear goggles to protect themselves.
Yes, most of athletes wear goggles not for fashion or so called cool, bur for shielding the eyes. You know, that it is really risk for athletes to take a game. And eye injuries are often occurred every years. In order to protect their eyes, some manufacturer produce goggles. With them, they can provide wearer good vision, as well as eye protection. In fact, it it very important to wear goggles for a game to athlete.
It seems that you are quite curious about that guy huh? Who is a very good baseball player in the USA. Anyway, it appears that he has got some myopia, in the meantime, with a pair of goggles he would be able to protect his eyes from damage or something. Of course he looks better with those goggles so it is just a fact of life I believe. Try to make yourself up then!