This article contains some common causes of unusual elo changes that you may experience:

Leaver Related Issues

What is the leaver penalty?

The leaver penalty is a punishment applied to players who are marked as a "leaver" in a match. This happens when you are disconnected from the server for more than 5 minutes. If you are marked as a "leaver" in a match, the match won't be shown in your history, and the match will not count towards any ladder or mission progress. 

Elo will still be awarded/removed based on the outcome of the match, but with the changes described below.

I was marked as a leaver and lost too much elo

Being marked as a leaver in a lost match will cause you to lose twice the expected amount of Elo from that match.

I only won half what I should have

If you are marked as a leaver in a match then you will only gain half of the expected elo from the match if your team wins, even if you join back afterwards. There is no way to get the full elo from a match where you were marked as a leaver.

I lost elo after winning a match

Being marked as a leaver in a match causes the match to not show up in your match history, so when you leave a match, your next match will likely show the combined elo change from those two matches on any third party extensions. This will likely lead to a negative elo being shown, as leaving a match results in double elo loss.

My teammate was marked as a leaver but I didn't lose half the Elo

If you queue with a player who is marked as a leaver, the Elo loss reduction (losing half the expected elo) won't apply to the players queued with the leaver. This also applies to 5 stacks.

Ban Related Issues

A player I reported was  banned but I haven’t received any elo

Elo is only returned due to a ban if all of the following conditions are met:

- a player is banned for either cheating, ban evasion, or smurfing.

- the match you played against him is within the last 100 matches the player played.

- the match is not older than 3 months.

Any other ban type does not revert any elo, including ‘playing on a smurf’ as this indicates that this is the player’s main account. This means that bans for Verbal Abuse, Unsportsmanlike Conduct, Ghosting , or similar will not return Elo.

A player I played with was banned and I have lost too much elo

If you played games with someone who gets banned for cheating, smurfing or ban evasion, you'll lose any elo that you gained from those matches.

On top of that, all the players who played against that banned person will get their points back, following the criteria written above.

This elo cannot be returned under any circumstances unless the ban in question is overturned.

Please note that the Elo isn't returned in case that:

- the matches that were reverted are beyond the last 100 matches you played

- the matches that were reverted are older than 3 months

- you have already won back all the Elo by playing and winning matches

Other

I didn’t win as much elo as I should have

Not every match will result in a +/-25 elo change (or +/-30 for Premium Super Matches). Elo changes can vary based on match balance, your party elo disparity or your personal performance in the match. Any elo gained from a match is calculated accurately, it is not possible to dispute your elo change from a match.