Found this thread on the 44th page of this section of the forum. You can probably tell her breasts were not always symmetrical. One of the best members of this forum ever. 
Is it just me or did her string implants yield the uneven expansion it was known for possibly causing? I never noticed that before on her.
String implants were known for being uneven. Chelse Charms had uneven breasts such as her right expanded sideways differently than her left breast for example. 
While I'm sure there are a variety of factors, Sol, I think placement is the most important. When the implant is placed with the imagined and/or actual size, I'm sure the surgeon does so with the areola/nipples facing forward. The problem is frequently seen with further expansion than the surgeon may have anticipated. No one could have expected Chelsea's reaction and the implants were likely medial to the areola to get the proper look post surgical - as I remember, they did face forward. Being medial, as they grew, rotation was rational as it reflected placement. We can see the same with Foxy; initially facing forwards, but when she got her implants, they were 2000cc expanders and that was the volume she initially sought, so I think placement was correct for that volume. However, Foxy fell into the boobie greed state of mind and her surgeon never anticipated she would actually expand to 10k, so once again, the rotation.
I'm fairly confident that surgeons place them as best as possible for the anticipated end size. Though I think this was also a bit of luck, you can see this with Beshine; her implants are enormous and a talented surgeon anticipated this before surgery. Still, though her areola do face forward, they are a bit medial as opposed to Foxy/CC distal, with her sideboob extending perhaps twice the distance as her medial boob (you can see this best on pictures lying on her back).
I was just not aware that Melonie suffered the size difference I had read did happen to many.