The then 17-time Grand Slam champion had just turned 32, lost to Sergiy Stakhovsky in the second round of Wimbledon (thus ending a run of 36 consecutive major quarter-finals), and then in straight sets to Tommy Robredo in the last 16 of the US Open.
Put it down, perhaps, to the impetuosity of inexperience, and also to unawareness of a significant back problem, which Federer later detailed.
Not that it was remotely controversial, nine years ago, to suggest the best days of a tennis player in their thirties might be behind them. It is just that since then Federer and Serena Williams, with Rafael Nadal and Novak Djokovic now following their lead, have overturned convention and expectation. [BBC]