Some good news again about Magic Metric. In the following link, you will find an interesting coparison between the rating system created by Dick Mays and other well-known indexes such as PER or Efficiency.
Beyond the interpretation of which system is the best based on the rankings created, you should consider the theoretical foundations of them. Remember that the Magic Metric rating system is grounded on a system of equations that yield the values of the linear weights employed. PER and Efficiency are much more subjective indexes.