And this, folks, is why NFL teams administer the Wonderlic Test.
Since there is no "blood test" that will measure innate intelligence and since the Combine does not last for two semesters where teams can see how players react to learning new things in a classroom setting, they have to settle for a quick test that correllates - - more times than not - - with innate intelligence levels.
I have taken the Wonderlic test several times in various evolutionary stages of the test. It is not perfect but I will say unequivocally:
If someone cannot score 10 or higher on the test and they are sober while taking the test, then the most polite thing to say about them is that they may be "intellectually challenged"...