So first to the last sentence: You said that good players vs good players would get - rating, but how could this session be made then? http://et.trackbase.net/session/61486/ 3 players with ~ 20 rating did play and get a + rating.
the average ppm is only 6 which means there were a lot of noobs on the server

So now to the other two sessions.
1) http://et.trackbase.net/session/368/
dtect got a minus rating of course because the av ppm was higher than normal, especially on fa#2 but also because he (with ~28rating points) did have the same ppm like a player with only 14 rating points.. As well there were pretty much guys with ~15 rating who did also pretty good ppms.
i see

2)http://et.trackbase.net/session/92160/
You did probably get minus rating because you had only 4 ppm more than a player which hasn't even got 10 rating points.
Of course the k/d ratio is important but you need to take into account which stats other players have had and how much their rating is.
hm i understand but i go TB to check how much + i had cuz i did good map only to find out i got - :p

the rating of the second best player and his rating
also: a good player could use a random name with low rating and do good ppm so the raters get - this is the way to get nr1

thx for infos Jonny