I went through all of the MLB rosters from 2011 to see which organizations active major league players came from. In other words, I wanted see see which organization drafted or signed the most major league players. I did include the starting lineups and all pitchers. I left off bench players. For example, Carlos Zambrano was originally acquired by the Cubs and Anthony Rizzo was originally acquired by the Red Sox.
The team that originally acquired the most MLB players as of 2011 was the Mariners.