Sure, and when the primaries are wrapped up and we've experienced months of Hilary and Trump head on who knows where we'll be. Point being GE polling will matter when we're actually in the thick of things, not this hypothetical barometer of where things stand now before the trajectory of the whole affair is heading in a completely different direction.
Clinton has been under the republican gun for decades. Aside from the occasional shot fired from the republicans at Sanders he really hasn't had to contend with the onslaught of what the right has in store should he be the nominee, which I doubt the GOP really thinks will happen, as much as they may want it to. The lack of offense Sanders has truly faced from the right wing establishment certainly plays into these GE polls, which is why I maintain that they, at this point in time, remain worthless. I do not see his numbers start to climb during the GE when the GOP opens the flood gates of advertising telling America that this godless socialist jew wants to raise taxes on the middle class (soundbite from months back, however right he may have been can be spun as pure poison by the GOP). I truly believe that Sanders as a GE candidate facing the GOP would be disastrous.
And then there's the supreme court.