But perhaps two organized team with teamspeak like in strat could deliver a final result, as they are most likely capable of showing the best performance possible for defenders and attackers, and how those best performances behave on that map. If this test has the result of a draw or close to it, you can assume the map is balanced.
Of course there is always the possibility that on pugs the results can vary. The reason for that is often that pugs rather play "instictively", and if somehow, due to map design, for one team the best strategy is somehow unconsciously suggested by the map, for the other team the map suggests something sub-par, the results will deviate. But I guess that's a rather special case.