I made a test with two players
A is 1.0d (rating 1920)
B is 9.0k (rating 1305).
Both have volatility 0.06 and deviation 65.
- They play an even game. If A wins then A’s rating increases by 0.7 and B’s rating decreases by 0.7. If B wins then A’s rating decreases by 23 and B’s rating increases by 23.
- They play a 9-stone handicap game. If A wins then A’s rating increases by 11.7 and B’s rating decreases by 20. If A loses then A’s rating decreases by 11.3 and B’s rating increases by 3.7.
This looks wrong to me. Assuming they both have 50% chances of winning, then each time they play a 9-stone handicap game, the 1d expects to gain 0.17 point (which is negligible) but the 9k expects to lose 8.2 points. In the long run, playing too many handicap games results in rank deflation.