World of Warcraft uses elo on a per fight basis in the arena, pretty sure Guild Wars does as well. Most video games that use an elo do it on a per fight basis. Usually top ranking scores like 2000 aren't hit until toward the end the season and if this is a three month long season we're only 1/3 of the way in. I should probably add that unless there is a clear imbalance what I say above seems to hold. I have seen players shoot up the ratings quickly but it was pretty obvious they were of a much higher caliber then the rest of the field and never lost.