Since your rank is an average of all 5 available ranks, So if someone is bulding away and some other nard comes along and masses their mothership, originally the defender had ranks of lets say, for example, 2,4,2,6,1
Which avg'd out equals 3... This individual would be rank 3, as long as somebody else didnt have a slightly lower average, a rank or 2 up on the AC compared to this person would make them rank 3 and this person rank 4 etc..
When someone comes along and masses that poor guys MS, he is left with ranks 2,4,2,6,1599
which equals avg of 322... This person will drop to rank 322, IF there are no other people there with a lesser average which may push them down a few ranks, if there are say 5000 inactive accounts that have a lower average then this person with the freshly massed MS, then they will fall to rank 5322 (example only obviously)
How is THAT possible... well, inactive players will obviously have ranks 0,0,0,0,0 / 5 = 0
Cant have a rank of 0, so they get placed riiiight at the back of all the accounts, but obviously when somebody loses a single stat and their average is thrown out, they can be ranked lower then inactives

Hope that helps you ph03nix

EDIT:
You may have seen times where I have forgotten to re-train my AC over a turn change, and drop from page 1 to rank 600+ all because of a single stat...
