This is not necessarily true. For example if the average height of all students is 5, and the average height of each class is 5 then the average of the averages will also be 5. While you are correct that averaging averages is unsound and could give a false result. Averaging averages does not automatically give an erroneous result. It would be interesting to do a detailed analysis of individuals to see if there is a significant difference from the server average.
i never even noticed the mercy rule until co-op went to 9v9 format. others have pointed out that people started complaining about it only after the 9v9 went into effect the answer should be simple, go back to 8v8 i will add that i don't care much for capping in co-op, but at least that was far less frustrating than having battles end early