In some examples, like elite college admission, it seems more like there are both negative and positive controls. Although colleges use SAT scores and GPAs to weed out people who aren't "good enough," they also look at whether students are exceptional through supplemental essays or awards the student received in high school. Negative controls bar many students from admission, but in many cases, positive controls must also be used to select a final class out of acceptable applicants. I'm not in academia, but it seems similar. Although you may get off the "track," you still need to do quality research to get a good position at the end of it. Even in top graduate programs, not all PhDs from those programs will end up finding academic jobs. At some point, you have to do more than just not fail.