It has been said in another thread that the result is predetermined 3 minutes before the game starts, which would be even sadder. If that is true, then your point about evenly matched league making results random is well made.
As far as a player going from 9 to 6, this is an everyday occurrence for me and I don't blame the game for it, but I have not figured out whom yet. I still don't know
a) how past ratings predicts performance in the next game
b) whether the rating affects the outcome of the game or other way around
Until I understand this better, I cannot get angrier or more concerned about inconsistent ratings than I am, which is not a lot.