rejections and production

  Hi, here's the link to a piece of mine that got rejected.
  Of course because of poor production and stuff like that, but can anyone actually tell what does it mean? Is it like arrangement, melody/harmony kinda things, or is it some sort of mixing/mastering and sound designy stuff? 
  The general commercial quality standard doesn't say a lot as well... can anyone explain what the standards of general commercial quality really are?

Thank you.