Well "The dominican" is correct as and adjective, of course. It is not correct as a noun.
About the baseball team shirts, it is just stupid. Not only it is ridiculous the way they use it, but also a little disrespectful. Remember when the shirt read "Dominicano soy"?, which was of course a direct reference to the Presidente beer slogan of the time. In any case, Serie del Caribe is a club tournament, not a country tournament. Have you ever seen the Manchester United wearing a **** reading "UK" instead of the team name while they play the Europa League? (I know, they don't have the team name either, but you get my point). It is also disrespectful to the champion team's fans, who now have to have their club name taken away from the team. As I said, it is stupid.
About the baseball team shirts, it is just stupid. Not only it is ridiculous the way they use it, but also a little disrespectful. Remember when the shirt read "Dominicano soy"?, which was of course a direct reference to the Presidente beer slogan of the time. In any case, Serie del Caribe is a club tournament, not a country tournament. Have you ever seen the Manchester United wearing a **** reading "UK" instead of the team name while they play the Europa League? (I know, they don't have the team name either, but you get my point). It is also disrespectful to the champion team's fans, who now have to have their club name taken away from the team. As I said, it is stupid.