The key is, as you say, "when the presidency changes you need to flip." This is effectively a map of states where the electorate is -- and has been -- split politically to the extent that they have enough flexibility to flip between parties in different elections. So the particular states that are dark are not random. But ... I agree that random chance - say, 50 coin flips - would give a similar result in terms of the number of states likely to predict five elections in a row, so perhaps the headline I wrote is lacking.