One conclusion to draw from this research Is that drafting and developing starting pitching by just one team is extremely difficult and an unreliable method for building a major league rotation. This is just one small slice of a much bigger issue--the best way to build a major league rotation for a team that limits its free agency spending. I don't think it is illogical at all to say that nearly all teams struggle to develop their own pitching. There are so many ways to acquire pitching talent and so many ways for the talent to progress. The OP only set out to examine a very small portion and discover a specific bit of knowledge. I would like to see further analysis along the lines of how a staff is constructed in an effective way for small and mid-market clubs. Maybe the case is that it takes 2, 3, or 4 teams/coaching staffs to unlock a pitcher's potential, especially so for non-elite talent. The accumulated knowledge and experience comes to fruition only after the original team has let go. Like an Arcia situation but for pitchers.