Tarell Alvin McCraney is just about to become a big deal. True, his plays have been produced all around the world, including in New York, but he has remained mostly obscure. That is all going to change when the 2016 film Moonlight hits theaters, which he has written the script for, based on his own play. It premiered Telluride in September to extremely positive reviews and is tapped to be a major contender this awards season. If you want to see one of the author’s earlier works before that film hits the mainstream, Theatre Rhinoceros is producing The Brothers Size in an effective, if slightly shaky, production.