I object to the term advanced metrics. In no way are.they "advanced". They are still statistics.The are just a different way at looking what happens during a baseball game.
We talk about objectivity vs subjectivity but when it comes right down to it, what is called a strike, what is called a hit, and what is called an error is based on a subjective interpretative. While the strike zone may be defined in the rule book it take an umpire to make the decision on what is actually a strike. The umpire makes a subjective determination of whether the pitched ball constitutes a strike as set forth in the rules. We know that there is wide variety between umpires in their determination of balls and strikes. So too when the umpire makes the determination of a close play at first or elsewhere. While instant replay may have some impact there is still subjectivity at play in many cases. So too when it comes to what constitutes an error. My larger point is that given the inherent subjectivity which lays at the very core of the game how does this effect mathematically the reliability and validity of the statistics. Just a point to ponder.