And to answer your question, no metric, old school or advanced, has shown actual accuracy in predicting the future. And if you expect them to, you will be disappointed often enough.
Statistics in baseball (all of them) are really just a measure of accomplishments, and while we all like to think those accomplishments readily translate into ability, they don't. They are a record of the past. It's a past we like to think can predict the future. but it really can't. You can hope to spy consistency and trends, but at the end of the day, you are trying to predict the actions of human beings, and even those who are the best at what they do have their weaknesses, frailties, shortcomings, and stumbling blocks that can skew any sample size.
Many have tried with varying degrees of success. But when it does come to small sample sizes, some of the old (other website) folks will attest, nothing predicts the future like a WAPM...