Original Post — Direct link
This problem really explains why rainbow six siege ranked is broken....

Earlier, my friend, who was playing ranked with me yesterday, had told me that a cheater was playing against us and that he had obtained additional MMR due to a sort of compensation for the cheaters/hackers that were present in that game. However, when I logged into my rainbow six siege account, it stated that:

"Players you encountered in Ranked matches have been identified as cheaters, so the effect they had on your MMR has been cancelled. Consequently, it was readjusted by removing 64 points."

Now, I wouldn't be so mad if the cheater was on my team and I was getting benefits for being one team with the cheater but, what really pisses me off is the fact that I played against the cheater and I was deducted points for that fact for what reason? For being in a game with a hacker? That's not even addressing the fact that my friend gained mmr instead of losing it. All of this had just elevated my saltiness towards this game and I am sure that the game with the cheater had been my lost. SO HOW IS DEDUCTING MY MMR EVEN MORE A COMPENSATION. All my hardwork to increase rank from silver 3 to silver 2 was demolished and now I got to even silver 4 so I am pretty pissed right now. GG
over 4 years ago - UbiMorning - Direct link
Hey there!

The amount of MMR rollback is subjective to how many banned players you played with. Most likely you played in matches with another player this season that was banned recently that your friend did not play with. The system rolls back MMR when ban waves happen and take the total amount of MMR impacted. In this case, the amount of MMR you won was more than the amount of MMR you lost from banned players, so you ended up losing some MMR overall.
It is also important to remember the amount of MMR you gain per match is not static, so it would also depend on how much MMR you have been winning/losing. You and your friend are not always going to gain the same amount of MMR.

As for the part about it being a compensation, we have explained in our rollback post that we have tested a one-sided rollback system, and found that MMR becomes inflated. It makes more sense to nullify the results of the banned player from everyone in the match, rather than just one side benefit. The goal is to revert impacted matches as if they never happened.

Let me know if you have any further questions!