Currently there are a number of meta-gamers on the site and I know that in time they will be found out and either warned or banned. I do report them if I'm over 90% convinced they are cheating, or sometimes they just admit it in a PM.
When identifying the less obvious cases I look at several things (bear in mind I'm referring to WTA Anon gunboats, how can you prove or stop meta:-gaming in full press games, how many 17-17 draws do we see)
1) In game how often they avoided taken an open SC in the Autumn and how often they support moves of other players.
2) In game when a country A from the beginning completely abandons any defense against neighbour country B and chucks all their units at country C, country B reciprocates by attacking country D, they save loads of time not defending their own SCs.
3) When player A is soloing and player B is helping them solo and making no attempt to stop them
4) I then do The Czech test, if some noob has better player stats than The Czech there is another warning sign.
5) Two players consistently do not 'READY UP' or do it together.
6) Then I go through their history, find the 3 or 4 players they have played most with, then take the average number of SCs earned when they play with those players against the number of SCs when playing with those players, the difference is usually so marked that it becomes obvious their outcomes are significantly enhanced by playing with each other.
Recently there seems to be a jump in new players (can the Mods confirm this stat.) and I believe the metas are using a bigger pool of User IDs that they mix and match.
The thing is I don't want them banned as we need a big pool of players to keep the live games going, my hope is that in time as the noobs improve they play games themselves rather than with their mates and so they bring some integrity to the games.
Even after looking at all these things I don't always report them until they really take the piss, Sarg was the first I spotted months ago but months passed before he was banned, I only checked him out because he was abusing me in PMs.
I think it takes a while to learn all the subtleties and nuances in a game, especially gunboats.
In saying all that I played someone last night who trounced me, one of the best players I've seen on this site, check out Azogar
http://webdiplomacy.net/profile.php?
userID=3149We need players like this playing more games, 51% win ratio, not bad eh !!