That's a bit embarrassing.
They're trying to make the case for superdelegate votes on the grounds that the polling regularly indicates that Sanders does better against all three Republicans still in the race than Clinton does.
Which is quite misleading as those polls have little predictive value. Even more so when you consider the GOP has been doing their damnedest these last 25 years to fabricate any scandal to use against Hillary (even openly stating that Benghazi was a success because it hurt her poll numbers), while Bernie hasn't been on the receiving end of any negative attention.
And speaking of Super Delegates: if you include them, then Clinton is only 242 away from the nomination (including the delegates that have been announced today). Most of the upcoming states will probably skew Sanders, but not enough to give him the election. Kentucky and Indiana will probably go Bernie in squeakers, as they mirror Missouri demographically. Additionally, there are the Dakotas, Oregon, and Montana which would vote for Bernie if the election were between him and blowjobs, and they were giving out free samples. However, all 6 of these states combine for 258 of the remaining 1016 delegates. Nevertheless, that is roughly the size of New York.