ok I give up, what's the deal with forfeiting

[Jellby]

In the standard 3-point game with cube, I know from personal experience that whether or not I lost 0-3, 1-3, or 2-3 (or any other situations, like being 1-2 and losing a gammon, making it 1-4) will result in a loss of different points on the scale for ranking.

Proof, or it didn't happen. The changes in Arena depend only on win/loss, and the opponent's rank (compared to yours). If you see any correlation with the game score, it must be coincidence. Or a new "hidden" feature of the site.

[Mort1mer]

I found this;
"When you win a game in Arena mode, you gain Arena points. You gain 3 Arena points when beating an opponent from the same league, 2 points when beating an opponent from league N-1, 1 point for beating an opponent from league N-2, and so on (and the same for higher leagues).
When you lose a game, you lose Arena points. However, you cannot go below 0 points."

This may explain my seeing different results of losing: it depended on our relative ranks and my position in my current rank.

It appears to have nothing to do with how many points one loses by in the match: 2-3 or 1-5, a loss is a loss is a loss.

This also explains the aggressive doubling that happens after an opponent has one game won: early doubling simply makes the next game(s) the decider for the "first to 3" match at realtvely no risk to the doubler.