The reasons for why questions were down-voted, and why they were closed are hardly related. They don't trigger each other.

However, there might be several reasons for explaining the correlation between the down-votes a question *may* get, and why it *may* get closed.

A question is not close-voted just because of the bad quality. There's no such [criteria][1] for close votes. However, if the question is still unclear after editing, then it may get down-votes, and be closed as it's "not a real question" or "too localized", etc.

  [1]: http://superuser.com/faq#close