Sarah Barley, children's and YA book editor at HarperCollins, responded in answer to a question:
"I think a fatal flaw might be an uneven or uninteresting voice. You can fix a plot, but it's really hard to fix something as subjective and as personal and intrinsic to a writer as voice."
I'll be spending the day evaluating the voice of my WIP.
I hope everyone who attended the online conference is busy pounding keyboards this morning with renewed enthusiasm for writing.