Critics say that the index is not a benchmark, rather a stock-picking strategy and as such there is no guarantee that managers using it will perform well in the future. What about those active...

Critics say that the index is not a benchmark, rather a stock-picking strategy and as such there is no guarantee that managers using it will perform well in the future. What about those active portfolio managers who charge high fees because they tell you that they realize superior returns? Are these excess returns due to alpha or their skill? Or are they due to simply mechanical investment strategies?