[notahacker]

It's less to do with social skills (agreed, there's no trade-off) and more to do with the probability that people scoring 6 out of 10 for their ability to discuss technical problems whilst getting 10 out of 10 for their ability to answer general interview questions are good interviewers with a weakness for understanding technical problems, whereas those scoring 6 out 10 for technical problems questions but 5 out of 10 for generic interview questions are likely underrepresenting their technical understanding due to the awkwardness of the interview situation. I'm also assuming that some common non-technical questions (like biggest weaknesses, and what they actually did in their last job) usually elicit useful information as opposed to answers synthesised from the job spec.

Since I've introduced arbitrary numerical scoring, I guess by "negatively weighting" I actually mean doing something equivalent to mutiplying their overall performance by 1 + scalefactor*(technical answers score - generic interview answers score) , but I'm assuming in practice most interviewers use their intuition rather than subjectively scoring every answer.

I'm assuming your amazingly productive friend aces the technical questions at least as impressively as the "convince me you'll have grown with the company after 5 years, even if you actually only see this as the bottom rung of the ladder" ones.