Part I described your Matchmaking Rank (MMR);
- internal / hidden.
- it's a probability curve of your most likely rank.
- accurately tracks your skill relative to others.
- adjusts quickly to form (more than you would expect).
- not so great for a visible rank.
Which brings us to your external / visible rank - the CSR.
If MMR > CSR you get more CSR for a win and lose less for a loss.
If MMR < CSR you get less CSR for a win and lose more for a loss.
Which is why you can't compare the post-game CSR changes between players. Everyone is on a different part of their ranking journey - and you don't know where their MMR sits in relation to their CSR.
Other potential advantages for CSR;
- you can cap the top level (Halo 3 capped at 50 despite having 70 ranks)
- you can add rank "protection" for a few games after earning a new level.
- you can have a different scale.
It doesn't even need to be the same as MMR.
Classic Halo used a scale of 1-50.
Halo 3 actually had 70 internal levels - but then capped the displayed rank at '50'.
Recent Halo games have used Divisions and Tiers.
The playing population is placed into a normal curve with a mean of 900 and a standard deviation of 300.
Each division is a standard deviation from the mean; Bronze, Silver, Gold, Platinum, Diamond, and Onyx.
Divisions (except Onyx) are divided into six 50 point tiers; I - VI.
Advantages of using Divisions;
- you can estimate the population in each (eg. Diamond = 14%).
- it "softens" skill gaps in match-making (eg. they were only one Div above me).
- you should go 50:50 vs your own division.
- you should go 75:25 vs the division below you.
- you should go 25:75 vs the division above you.
There doesn't seem to be any influence of performance in the game just played.
MMR does take into account kills per minute (KPM).
So KPM has a lag effect where your MMR pulls on your CSR in the next game.
2. A game mode is chosen.
3. A map form that mode's pool is chosen.
4. Teams are then selected on the basis of MMR (better reflection of form).
5. The game is played.
6. CSR is allocated on the basis of the result and pre-game MMR.
7. MMR is adjusted on; result, skill gap, confidence, and performance (KPM).
8. And onto the next game...
Choosing lobbies based on CSR is a bit silly. It was a concession to disgruntled players to make the game "look" fairer. Even though the reality is that some players MMR can be very different to their CSR (post placement or Smurfs) and it can actually make the game more uneven. Especially if squads are in the mix - reducing the option for team selection.
Everyone is on a different part of their MMR journey.
You can't see your own MMR, let alone anyone else's.
If their CSR changed by more than yours it simply means they have a bigger gap between their MMR and CSR.