A few things changed. Pollsters realized that polls can impact the result of a election, people who lean for a particular candidate can be pushed over the edge

A few things changed. Pollsters realized that polls can impact the result of a election, people who lean for a particular candidate can be pushed over the edge with a poll that shows that candidate winning. Half the country has been classified as deplorable and have learned to not express how they feel to others, it shows up at the ballot box but you don't see it when you survey.