Carmack is a long way short of the most awkward public speaker I've seen. Carmack knows what he's talking about, and can monologue stream of consciousness from that. Far more awkward is watching someone who only just barely knows what they're talking about, but gets tripped up by e.g. interjections or questions from the audience. You see it a lot with consultants doing presentations at conferences, pretending competence in some domain or other. I can find myself either cringing with embarrassment on their behalf, or shaking my head in disgust, depending on the personality and the degree to which they try to BS their way through.