<p>SBdad:</p>
<p>I don’t know enough to make an informed comment, but just going on what you say, I suspect your S believes too much that jobs are only about qualifications. They are a bit more like college: adcoms look beyond the stats to build a community. Companies look for people who will get along well with others. This does not mean just not being fussy or a trouble-maker, but being able to make the work environment more pleasant and collegial.
So someone who comes across as overly serious, who does not crack a smile, may not present himself to the best advantage. Your S does not have to try for Prom King. But perhaps, he should be a bit more relaxed, while also appearing enthusiastic and knowledgeable about the job and the company. It’s a tough balancing act, to be sure, but perhaps, he could practice for the next time he goes to an interview.</p>