Every season is a chance for prospects who are going to be Rule 5 eligible to make a case for a 40-man roster spot. The Pittsburgh Pirates have plenty of notable names in their minor league system, and they will have to make a choice at the end of the season that could determine a few test case's organizational fates. They should have enough 40-man roster spots to protect some important minor leaguers, but some notable ones will likely end up getting exposed to the draft either way.
If they protect anyone, these four should be the first ones they consider.