as explained a few posts above, winning is sometimes not enough to raise your ELO.
If you want to be sure to not see your ELO dropping you must not lose more than 1 game per set (or even match).
For example, if you play against someone who has an ELO of 800, and you beat him only 6/4 with your ELO of 2200, it means your ELO is too high and his ELO is too low, therefore your ELO will lower.
And if you beat him 6/0, your ELO will probably not change.
== Mana Games ==
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