The US teams have only participated in half the events compared to the leaders. Not saying that would catapult them to the top, but surely it would help. Here is a per event comparison (not that it is really a great tool, but it is another data point):

Sarah/JC average 125.5 points per event

The current #1 averages 155.8 points per event
The current #10 averages 126.3 points per event
The current #15 averages 111.5 points per event
The current #20 averages 115.3 points per event
The current #25 averages 97.3 points per event

Over a full season with equal participation, Sarah and JC would move into the top 20 at least (maybe top 15).