alanback: Yes, for the reasons you said it is better to use the rating at the end of the match, as it is done.

But I don't understand your last remark about backgammon ratings. Since they don't work properly, backgammon tournaments with a BKR limit are skewed anyway, so the eligibility problem sort of vanishes. It remains a problem when the BKR is reliable though.

coan.net: Your example of a player timing out in all games looks unfair at first glance, but in fact it would be even more unfair if the ratings were taken at the beginning of the game. The rating points won by those timeouts are undeserved anyway, so the fewest points won the better.