I would dispute that, purely because it says on FP's website that the rankings come from WM's TRIP report: http://www.foreignpolicy.com/articles/2012/01/03/top_ten_international_relations_masters_programs
You're right, it is published in FP, but WM does the research, even in 2011. Here is the link (pg 27): http://irtheoryandpractice.wm.edu/projects/trip/TRIP%202011%20RESULTS%20US%20RESPONDENTS.pdf