Nope. It is from wiki, actually. You are not reading. Clearly, The post starts saying , according with wiki....
Again, you are rating the size of a market place/territory. We are talking about the size of a market team. As the definition says, it is related with media market coverage. Hence I asked what is the Nats' media market coverage in the US?
Do you realize that fanbase/popularity is related with media market? Nats' popularity, even in their own town is questionable. Read the article that I already posted. Nats games are not attractive. Buying advertising in Nats' games is not attractive and/or cheap compared with Big Market teams. Again, Nats are not a big market team.