Having had a lab partner who in Senior year EE couldn't do even the most basic things, I sympathize with you. But you need to consider what that person knows "as a whole." I've found that if you take the time to talk to graduates who were poor students that they do have a basic understanding of the subject matter, but there are gaps. The gaps tend to be most noticeable when they're really simple things, which I think is the point you're making.

Contrast that with someone who has say, a History degree who happens to be a good programmer. That person's expertise tends to be in one narrowly defined area and when taken outside that range he does badly. I'd rather hire someone who had promise to be reasonably good at anything I threw at him than amazing in one aspect and weak at most everything else.

I don't know where you work, but the people who make it through both our HR screen and the technical phone screen and end up in front of me are generally pretty bright. We normally weed people out for teamwork/communication skills rather than technical ability.