I heard from half a dozen people with their theories about why Beth Wood is significantly out polling Les Merritt but the most plausible came from one of the wisest veterans of North Carolina politics: a Democratic woman is going to beat a Republican man.
There's a lot of validity to that. Democrats lead in 4 of 5 Council of State races where they've nominated a woman running against a man, and I imagine Janet Cowell is going to end up winning this fall as well. In the 5 races that don't fit that description Democrats have the advantage in only 2.
It just is not plausible that a significant mass of voters are choosing against Merritt because of his job performance. Given that Civitas recently found less than half of the state's likely voters know who controls the Legislature, I'm guessing even less know who the Auditor is, and even less beyond that have an opinion about his job performance one way or the other.
At the end of the day the why doesn't matter all that much- at this point Beth Wood is the clear favorite to beat the incumbent.