You're being skeptical for the wrong side. We humans have a long, inglorious history of inventing objective metrics that absolutely fail to be useful at predicting the things we want to predict. From the IQ tests to the NHL combine, we're traditionally quite awful at inventing predictive tests of performance.

Which is to say: if you're being intellectually honest, you should be far more skeptical that a test does what it claims to do, than you should be of the opposite argument.