If you’re worried that you’re not getting your fair shake in the ranking system, look at the last 50 games that you’ve played in that hopper. (If you haven’t played 50 games, play more. The system needs more data.)

Take your win/loss average. If it’s 65% or above, and you’ve been in that playlist for a while, you’ve probably increased in level 2 or more times over the last 50 games (or you will in the next 20 or so). Otherwise you are going to be hovering around the same level or dropping in rank.

Trueskill DOES NOT take into evaluation performances inside the game. The ONLY statistics that Trueskill takes from a game are the Mu and Sigma values of all the players, and how you placed.

This means that out of all of these statistics:
Getting the MVP
Having a High K/D ratio
Getting the most medals
Skill levels of those you killed / killed you
Weapons you used
Headshots
Captures, detonations, stops, ousts, etc.

NONE of them matter when calculating the Mu increase/decrease. Any link between any of these and the skill ratings are purely correlative and not causative.

For example. When I play Team Slayer with my buddies on my alternate gamertag, much of the time I end up carrying the team. I created this tag to play with my buddies, and as such, have only ever played on that party with that tag. I ranked up to the level of my friends within 20 or so games, while it had taken them 50 to 100 games to reach their level. My friends thought that it was because of my frequent MVP status and my high K/D ratio that I leveled up so fast.

Wrong. I leveled up fast because A) I initially had a very high Sigma, making my Mu more variable after each win, B) Starting out at a 1 and playing people in the mid teens gave me a considerable boost every time I won, and C) We won more frequently than they had in the past.

The Trueskill system is a player skill rating system for Xbox Live. Halo 3 uses a version of the Trueskill system in order to make the matches fairly even.

Trueskill assigns skills on a normal distribution (bell curve, Gaussian). The Trueskill system has two main variables to consider. They are your player skill level (Mu) and your uncertainty factor (Sigma).

Mu is an approximation of your skill level based upon past performance. Win games to raise Mu, and lose games to lower Mu.

Sigma is the numerical representation of the range in which your true skill could lie. Play really consistently, and you have a low Sigma. Play streakily, and you have a higher Sigma.

After a win, the Trueskill system adjusts your skill ranking based upon the Mu and Sigma of all the players in the game. We’ll go deeper into how much it is adjusted later.

Trueskill systems use a conservative ranking Ranking = mu – (K * Sigma) so your skill is likely to be higher than the actual number represented in your Halo 3 highest skill level. K is a constant assigned an arbitrary value by the developers of the game.