You always hear about QBs being late round picks as developmental projects that could be future starters. Here is an article that breaksdown all the QBs in the league who are starting and shows how developing QBs doesnt really happen as much anymore. He also provides a theory of why (lack of playing time and practice time with/against 1st stringers) which seems relatively plausible, especially in the future, given the reduction in practice time with the new CBA.