often wrote:liang wei tang 9p once told me that for amateurs, a 10-20 point loss in the joseki/opening might as well not really be a loss. his reasoning was that so much happens in the middle game (swings/deaths/etc) that you can easily make it back.
It is true that amateur plays are worth less than pro plays, on average. But the difference is not that great. If the correct komi for pros is 6.5, then maybe correct komi for amateur shodan vs. amateur shodan is 5.5. The reason for the difference in komi is that amateurs make more and larger mistakes than pros. Even so, the difference is small.
So, to simulate the 10-20 pt. loss that Liang talks about, let shodan play shodan where White gives 7.5 komi. What are the odds that Black will win? My guess is around 2:1. But we actually have some statistics on similar mismatches, because a lot of tournament games pit unequal opponents in even games. If nidan plays shodan even, what are the odds that the nidan will win? Does anybody think that the nidan does not "really" have an advantage, because the shodan can easily make up the difference?
I do not think that Liang has thought his remark through. Perhaps he observes the large and frequent errors in amateur games and thinks that there will be opportunities for a player who is behind by 10-20 points to make up the difference. That is so. But the player trying to make up the difference is also an amateur. Liang could surely make up a 20 pt. loss in the opening of an even game against an amateur shodan, but the question is whether another amateur shodan could do so. Not likely.