It seems reasonable that there would be some relationship between traffic to Prosper and traffic to Org.
Looking at the Org site statistics, as provided by Org's on-site stats page, I am not seeing the 65% month-to-month drop (assuming it's comparing Jan 10 to Dec 09).
If the Org stats are off, the other stats may also be suspect - although the query does caution that the sample size for Org is significantly smaller.