In PR2, it can take almost 600 games for the system to determine my rank. Supposedly only 100 of these games count. It would be nice to be able to review only the games which count.
I think all games count (except in case of draw). For me, the 100/100 is just a percentage and not the number of games that determines your rank. 
All games don’t count. If it is an asymmetrical map, and you win one and lose one it is thrown out. I think this happens quite a bit when you get into the upper parts of the leaderboard, since the position on the map becomes a lot more important.
Each time there is a battle in an asymmetrical map, the next battle is on the same map with the positions reversed. So this in not imbalanced and I believe these battles are also taken into account (plus, if you win both, it means you really are better than the opponent).
They are NOT taken into account. Read this post from a CodinGame admin: Platinum Rift II - Your rules
If you get one win each in an asymmetric game, the game is not fed to TrueSkill, it is simply thrown away by our system…
OK, my bad. Why did that rule ever made it to the game so? I’m puzzled. Plus, I already hated going through the “latest matches” list and seeing asymmetric matches that clutter the list, now that I know they are meaningless, it is even worse!
Maybe I will modify my code to check if the map is asymmetric and just quit if it is.
If you just quit on an asymmetric map, you will lose that map because the opponent will win both sides.
I seriously need to start reading more slowly. I did not see that it was only in the case of a tie (one win each) that it was thrown out.
I just dropped from 27th to 346th place…
Yeah, so my last battles list this time is 1600 matches. And I don’t know which ones counted towards my rank and which ones were thrown out.