The ATP analyzed the statistics and showed that Federer actually plays better tennis when he is ranked #1 than when he is not:
In his tenure, which first began on 2 February 2004, Federer has won 417 of his 469 matches (.889) and lifted 46 of his 76 career titles (.605). Without the World No. 1 ranking, Federer has gone 454-143 (.760) and captured 30 trophies.That being said, with Novak Djokovic's epic comeback win at the Shanghai Masters over Murray he know is well over 2,000 points ahead of Federer for the calendar year and since there only 3 more weeks of competition remaining in the year, Federer will have to repeat his amazing 17-0 end to 2011 when he swept the Swiss Indoors, the Paris Masters and ATP World Tour Finals in order to have a chance of ending the year at #1.
Incredibly, he has lost no more than 10 matches as World No. 1 in any single season except 2008, when his record streak of 237 consecutive weeks at World No. 1 came to an end on 18 August, at the hands of his great rival Rafael Nadal.Since February 2004, only two players have been able to wrestle the World No. 1 ranking away from Federer. By comparison, Nadal compiled a 140-22 mark (.864) and won 11 titles in his 102-week total stint at World No. 1, while Djokovic lifted four trophies and went 63-13 (.829) in his 53 weeks, which started on 4 July 2011.
Regardless, 300 weeks at #1 is an astonishing achievement. Congratulations!