The average fan can easily calculate a player's batting average , home runs , RBIs , OBP , etc. Also , they can easily see a pitcher's wins , losses and saves. ERA and WHIP are also easy to calculate. However , that fan has no idea how fWAR is calculated. I dare say many of the folks who love that stat also don't know how it is derived. How many folks could sit down now and figure out a given player's fWAR . You are basically just trusting someone who has some sort of system. I am not saying that it has no value , just that the average fan simply is not that interested. And that goes for the whole , ever growing , alphabet soup of metrics as well.