A provocative title, I know. But just so we’re clear, it’s a generalization. Not all extraverts have good social skills and many introverts have excellent social skills–maybe good enough that people will accuse them of being extraverts.
It’s helpful to define the terms, terms generally misunderstood by the general public. For simplicity, we’ll say that introverts generally direct attention toward internal stimuli while extraverts (also spelled extroverts) tend to do the opposite (that focus toward external stimuli will often include but not be limited to interpersonal interaction, of course).
There are opinions as to why someone might fall more on the introverted part of the spectrum than on the extraverted side, more so than I can discuss here. My take on it is that there are potentially multiple causes, with some variables applying more to some than others. The most obvious is the “cortical arousal” argument. Introverts might be higher in basal (normal) arousal/activation levels, and/or might experience greater autonomic arousal due to non-controlled external stimuli. In other words, introverts might stress out more easily, and so might avoid excessive external stimuli that would further augment that stress.
These again are generalizations. Show me an extravert with a moderate social phobia and I’ll show you someone who is awkward in social situations as well, I just happen to believe that’s very uncommon. The other side of the coin though is more common: many introverts are adept in social situations, some are exceptionally good, and they’ve played to their strengths, drawing on their tendency toward focusing inwardly to give them greater efficacy when dealing with or confronting potentially daunting social encounters.
So to summarize, many people, often introverted, come across as awkward, tense, or generally maladapted in social situations, namely in more stressful encounters or in novel situations (new people, or large groups, or whatever). This isn’t a characteristic of introversion per se; it’s correlation rather than causality. I’ve focused so far on social stress, meaning that anyone who experiences elevated stress in social situations might come across as awkward, tense, etc, with the evidence in body language (tenser and jerkier movements, defensive stance) and in vocals (abnormal elevation in loudness and/or difficulty regulating one’s volume, elevated pitch, etc). Other factors undoubtedly come into play, such as “emotional intelligence” factors, such as capacity to understand the emotions of others with whom you’re speaking.
Solution to this problem? Absolutely. In fact, I’m living proof as to the malleability of one’s personality (though the malleability of one’s personality might itself by a personality characteristic). First and foremost, identify ways to reduce your tension/anxiety during social encounters. Think of people as benign objects rather than people–temporarily–if that helps, so that discourse becomes more relaxed. Utilize tactics such as speaking to one person at a time rather than larger groups when possible. Learn to better understand and regulate your own emotional state; be honest with yourself as to the emotions you’re experiencing (avoid certainly unhealthy defense mechanisms which would mask this information from you), and formulate healthy ways of channeling those emotions positively rather than negatively or divisively (and if you’re introverted, you are more negative than extraverts, statistically speaking).