Ranking the players with the average number of kills/deaths per match isn t a good idea...Someone coming 5 min before the end of the game will screw his own stats.
You should rank according to the time played (since its also logged by the server). Of course a late joiner will have trouble killing S3 people, but that wont affect too much his ranking (since a full game will be worth 12 times more than the 5 min one).
As for the chat logs issue...What is the point

? Who will read entire chat logs

? for what purpose

Its not like its really interesting..."decon reactor, building reactor, omg human campers, owned, gg..." Really i dont see whats the point of adding them. If some people doesnt wanna the whole chat logs to be posted, since its utterly useless, you shouldn t add them.
Also, you might want to speak to DASPRID, you released its own stats system. Might be useful to share your experience and troubles (for example yesterday he was trying to tackle the problem of colored nicknames on IRC), and maybe merge your codes ? Having 2 stats systems seems a bit too much for one game.