A friend alerted me to this essay by Nate Silver:

"So here’s another question. What would have happened if just 1 out of every 100 voters shifted from Trump to Clinton? That would have produced a net shift of 2 percentage points in Clinton’s direction. And instead of the map you see above, we’d have wound up with this result in the Electoral College instead:"

(...)

"Michigan, Wisconsin, Pennsylvania and Florida flip back to Clinton, giving her a total of 307 electoral votes. And she’d have won the popular vote by 3 to 4 percentage points, right where the final national polls had the race and in line with Obama’s margin of victory in 2012. If this had happened, the interpretation of the outcome would have been very different — something like this, I’d imagine:

Republicans simply can’t appeal to enough voters to have a credible chance at the Electoral College. While states like Ohio and Iowa might be slipping away from Democrats, they’ll be more than made up for by the shift of Arizona, North Carolina and Florida into the blue column as demographic changes take hold. Democrats are the coalition of the ascendant.
The United States was more than ready for the first woman president. And they elected her immediately after the first African-American president."

(Read the article here.)

Elections and soccer have much in common. So-called experts, or perhaps even real experts, look at the results and jump to conclusions, ignoring the fact that the margins are fairly small (elections) or that a bit of luck or a hapless referee can change a match completely.