If I were a pvper, I'd be flipping tables.
I facepalmed when I armoried one of the guys who plays at the 1550 level in arenas but somehow manage to go from 1600 to 3000+ rbg rating in 2 days. >.>
We're taking a look at armory data as well. It may not be as accurate as we'd like it to be. We'll keep everyone informed should we make any further updates on it though.
Don't have some sort of program that can look at highly rated people and then look at their win/loss ratio and be like: "3k rating... 11 wins 8 losses... that don't look right..."
Once you inspect that guy you can begin to see who he associates with since it is likely anyone he RBGs with is also involved. I'm sure all this data can be data mined. Things like looking at how long matches have taken. What do the scoreboards look like.
The big problem you guys are going to happen is people are going to see this and be like "well they are clearly doing it and not getting punished anyways, maybe I should do it too now". Win trading is nothing new either. I remember hearing about it in wrath. I would of thought you guys would of refined the methods of quickly catching onto this and punish people either mid season or at the end of the season even without the support of players catching it. You guys mods that can just watch the forums and delete posts all day. Maybe towards the end of the season a guy could take a day or work and just look at the PVP top rated listed and just look at the people with really shady records.
The point is it looks like while I'm sure you might have some looking into this the best they can as an organization it doesn't appear that you guys have been taking this subject as seriously as you should. You readily "watch" high end raiders go through PvE content even swiftly punishing those clearly abusing the system. You even seemed to of caught on the LFR abuse in Cata when it first launched. I remember hearing of temp bans for a guild that was using the whole saronite bomb trick vs heroic Lich King. For abuse of win trading it seems you take more of a "bot investigation" approach where you let these people win trade for essentially ever. I know we players can be your greatest source of information of catching bad players at times but this game is full of stats, figures, and things that can be monitored by your systems.