The SeatGeek founder's answer to the question you're referring was actually much more useful than it seemed when you look at it in context. He was able to say that ticket prices for baseball games varied by 40%, on average, over a month... for sold out games.
Although pg seemed dissatisfied with this response, and was looking for ticket price variation for all games, why should the SeatGeek guys know that? It's not important to their business, because their service is only valuable when there's an active secondary-market for ticket sales, in other words, when tickets for games are rare, which most of the time is because they're sold out.