What are the rules for sorting in the Gallery forum?

Currently MURDERBALL is sorted as the 2nd image (left to right) yet it has no new comments for a long time, it's time is older than some others, it's view count is low compared to others, etc.
I see nothing obvious to indicate why it's the 2nd image in the Gallery.
I thought the outside Island was semi-random but it looks like maybe the Gallery is as well ?

Is there some type of control for sorting in there by an Admin?