It's exactly what it is. When someone enlists in the US military, they take what is called the ASVAB (Armed Services Vocational Aptitude Battery). It's more specific to the military than Stanford-Binet, but effectively it is still an IQ test. Specific military occupational specialties have minimum score requirements to qualify for that job. Which job you actually end up getting is a combination of scoring high enough to qualify, scoring higher than everyone else who wants the same job, doing well on other things they assess you on, and needs of the branch of service at the time you enlist. Score high enough for cyber but they only need mechanics, then you're becoming a mechanic. Conversely, if they badly need cyber professionals but nobody scores high enough to meet the official bar, they're still putting people into that job. Hence, why the mismatch exists in the first place and why there's a study like this.