Best performer of 2012 in terms of points accumulated but Federer is the best player in the world according to the computer rankings which go back 365 days.
The race ranking is not the world ranking.
Federer is the best player of the year. Won the most important tournament, won the most tournaments, won a silver at the OG as opposed to no medal, and of course he is #1. If he wins the WTF he will be the best player of the year no matter the rankings.