Originally Posted by LuckyR
I agree that this is the likely explanation for what happened, and I agree with the use of the word: "flaw". Sometimes more complication, calculations and rules lead to illogical conclusions like this case.
Perhaps my use of the word flaw was a little strong. It is just how the system behaves when two players partner at doubles all the time. The gap between their ratings will be maintained.
Without some other matches played with other partners and/or singles matches to otherwise adjust one of the individuals ratings, what alternative do you suggest for this situation where matches are always played with the same partner?
You can't just arbitrarily shrink the gap between their ratings as that too many not be correct and may not give the credit due to the higher rated partner. We've just looked at one situation where the big gap seems like an error but I'm sure there are others where a small gap would similarly be an error.
It is just the nature of a system that calculates ratings based on limited data. It isn't perfect, but it is better than many alternatives.