It is relatively easy for us to get trends and results right after the fact.
Folks doing and interpreting all the polls but one had Clinton winning. All but one who estimated the probability of winning had here as a huge favorite (75% or more).
In the end, what mattered was the turnout of various groups in PA, MI and WI. Hillary's campaign choices in the last week made the difference with regard to a lot of these voters. The huge Beyonce concert to show who her voters were didn't help with rural voters. A lot of Bernie's youngsters just didn't come out to vote. The vote was very close in all of these states.
What the pollsters got wrong is the turnout in various groups.
And yes, many folks warned Hillary (for many months) that the working class vote in the Mid-West was critical, and that she needed to campaign there. Hillary simply wouldn't listen to the unions there, to her husband or to Obama. Considering just how good her husband and Obama were at winning, one would think that she and her team would have had a bit more respect for their advice.
And yes, it strange, but likely true that if had held her final concert had been held in Madison WI and had included primarily country singers, she likely would have won.