Not to mention that it's not even possible to turn over 15 players in one trade period. Once you consider how any players are under contract, how many trades are available and how nobody takes anybody in the draft after pick 90 - no club is turning over more than 7-8 players max. I think I read somewhere that there is a limit on delistings too?
Carlton turned over 15 in '15 and a total of 40 in the past three years.
No limit on de-listing either.