I recall a skater who had the lead after the SP at Nagano and SLC who could not close the deal.
Burn! Oh snap
prepare for the onslaught from that skater's fans! 
As for Nagasu- she is really only competing against one person- herself. Once she can beat "herself", she can beat anyone in the US. And be a world medal contender- perhaps even title contender. But does she have the competitor's mentality? Unfortunately I do not see it in her at this point.