In a nutshell? Sure.
Speech habits, login/logout times, message times, opening moves, reactions to others opening moves, backstab habits, total points, points in play, and of course past performances sorted every which way by country, game type, other opponents, etc.
These sources of data, to name a few, all help to determine who is who in an anonymous game, help to predict opening moves, help to know when the player will be online so I can have long chats or know who's talking to who, help force out stabs or prevent them. Gunboat games even help predict moves in press games when press is purposefully not given. Live games are especially vulnerable because people tend to revert to what they know when under the timer's thumb. There are probably angles and uses that I haven't even thought of.
That is the most difficult part. Using the data. Visualising the data. That's where Realpolitik lent a hand. Sure you create a file on your opponents, basic data like online times, best and worst countries, ancient forum posts they cared about (make friends over the same off topics and players respond), again etc. But looking at moves, seeing the animations, watching a list of the most likely moves of your opponent against a list of your own most likely moves? You need an adjudicator that doesn't mind being told what to do.
It's important to note that this was quite a while ago. Certainly before I was approached about becoming a moderator. The project was successful in some areas and a disaster in others, the most useful FBI file that came out of it was the one on myself and it made me stop crafting lies, which is my favourite aspect of Diplomacy.
Plus, right after Boston, me and MM got in an argument over the usage of said data and he pretty much hit the nail on the head with "I haven't checked your stats, but have you won 100% of your games, and if not, why not if all this data is so damned valuable?! I don't pay attention to jack shit and I'm doing well enough. The defense closes, your witness." Though I speculate some of the conversation helped him decide to make his double-blind invitational. =P
And don't ask me to share any of it with you. I'm not even sure where the majority of the stuff is let alone the desire to pick through it and I really don't think it was a good idea to begin with, a fun project at best, but if the goal was becoming a better diplomacy player, the time would have been better spent elsewhere.
I've got to go convince all the restaurants on campus that lasers are going to save them thousands and thousands of dollars. Been working on this presentation for weeks, haven't slept, and just realised I don't have a clean pair of socks. Wish me luck!