The Pirates added an additional rookie level team in Bristol before the 2014 season, essentially replacing their second DSL team (which went away that year) and moving the extra team up a few levels. Bristol falls between the GCL and Morgantown on the talent scale. The average age is about half a year older in the Appalachian League than the GCL, so there's not a huge difference between the two levels. They're both classified as rookie levels, while Morgantown is short-season A-ball.
The Pirates have used this team as a middle ground the last few years. And for the most part, it hasn't featured a lot of talent.