If the results had been different, our prediction would have been correct. First, that comment is about the polls, not their model. Second, it's called a poll

If the results had been different, our prediction would have been correct. First, that comment is about the polls, not their model. Second, it's called a polling error. It's actually a thing. This election happened to be extremely sensitive to polling errors due to the nature of the electoral college and the fact that a number of key races were extremely tight. When an average poll has a 3% margin of error, and you factor in state-level correlations (and the fact that the state level polls tend to have more variable quality than national polls), a slight error results in a huge swing. Which is the entire point they're making, if you're willing to set aside the snark and read what they wrote (since it's actually, you know, interesting and informative).