http://www.baseballamerica.com/today/majors/season-preview/2012/2613177.html
That's an article that was written before last season. Among other things it points out that about 100 of the roughly 1300 players on 40 man rosters were drafted in the 20 th round or later. They list some notables in this category. I didn't see a lot of common teams among those, with the possible exception if three giants pitchers. There is as heavy tilt toward relief pitchers and lumbering hitters mostly 1b
Spencer is right, teams don't give low picks much opportunity, because they don't think they are any good. If they did, they would have drafted then earlier. The guys that make it usually find some way to greatly improve in what scouts thought was possible.
Without question, there are trends that are better and drafting and there are teams that are better at player.development. But how can we define which is which? Low draft picks making it are rare. They happen when a skill or two appears where scouts thought there was none.