This isn’t an exact solution to the problem you highlighted, but here’s one change I did make just now.
When we started to take into account the past war history, we capped the effect to 10 consecutive victories or losses. There are a lot of alliances who have reached both ends of the spectrum. I’ve now increased the limit to 20 wins or losses.
We’ll monitor the situation, and feel free to comment on this thread if you think it made things worse and not better. I reserve the right to bring the limit back to 10. 