Well let's be honest, the only reason Hillary has done so "terribly" during these primaries is because she's been up against and opponent who has refused to drop out at almost every normal juncture where a regular candidate would have. That's why these fractures exist and why it's the second closest Democratic primary in history. Hell, there were compelling reasons for him to drop out after Super Tuesday, but certainly most regular folks would have gotten out after the rout in Ohio and all those other states that night.
Him staying in has kept it "close" only in a pretty phony sense. And again, his selfishness continues to hurt the party and make Hillary look "weak" even though there's very little truth to that. It all about appearances.
I think this is self-inflicted by Clinton. The traditional move at this point would be an olive branch and some concessions to create a united front. Has she done anything beyond demanding that the Clinton flag be run up the flagpole, and that everyone salute it?
And it's not just Sanders. She's going after Trump on effing GUN RIGHTS. That's an idiotic move on so many levels. It looks like she's going for a Fool's Mate on herself.
My current hope is that she goes down in flames before the convention and we get a competent politician instead of Hillary. I'll take pretty much anyone, from Sanders to Biden to Webb.