The poll says that of the likely voters Hillary will get 5% more than Obama got over Romney. The poll doesn’t say that Hillary will get more voters in this group to the polls. It doesn’t say that she will attract more likely voters.
Nicely done: a careful reading of the text will reveal the comPost’s deception.
What you seem to be saying is this:
Hussein the fascist may have attracted 78 millennials for every 22 Romney got. Hitlery may attract 83 for every 17 of Trump’s.
But that is a mere percentage number. What isn’t reported is the raw number—so in 2012 the total number of millennials voting might have been 25,000—whereas in 2016 the total number of millennials voting may be around 14,000. (I am using low examples just to make the point.)