Right now, the weakest part of the Pittsburgh Pirates roster is likely their starting rotation. The team does not have a bona fide ace or even one that would be considered a top of the rotation type arm. Part of this is due to the lack of development of pitchers from the previous regime, but also a focus on finding more hitting prospects over the last few seasons.
Over the last year or so both former General Manager Neal Huntington and current General Manager Ben Cherington have started to invest more resources into acquiring pitching prospects.