Arrogance
You hear all this talk of the mental battles between Djokovic and Nadal; "Oh, if Djokovic loses the Australian Open, it will take away his confidence and he will suck", "if Djokovic beats Nadal at the French Open it will destroy Nadal". Or you hear about "Nadal lacks confidence on hard courts, if he loses to Djokovic it will hurt him", or "Nadal lost his confidence on hardcourt."
Prime federer never had those issues. Because of his arrogance, even if he lost to someone or didn't win a slam, he wasn't fazed at all. After missing two straight slam finals in 2005, he made the next 10 slam finals. After losing his streak of 10 straight slam finals at AO2008, winning only 4 games in the 2008FO final, and losing to nadal at the wimbledon, he went on to come within a set of winning the next 4 slams. Federer never had these confidence issues in his prime because of his supremer arrogance. Even if he lost, he believed that he was supposed to win. Perhaps this same arrogance prevented Federer from improving his game, but it certainly helped his consistency as he never had real confidence issues.
You hear all this talk of the mental battles between Djokovic and Nadal; "Oh, if Djokovic loses the Australian Open, it will take away his confidence and he will suck", "if Djokovic beats Nadal at the French Open it will destroy Nadal". Or you hear about "Nadal lacks confidence on hard courts, if he loses to Djokovic it will hurt him", or "Nadal lost his confidence on hardcourt."
Prime federer never had those issues. Because of his arrogance, even if he lost to someone or didn't win a slam, he wasn't fazed at all. After missing two straight slam finals in 2005, he made the next 10 slam finals. After losing his streak of 10 straight slam finals at AO2008, winning only 4 games in the 2008FO final, and losing to nadal at the wimbledon, he went on to come within a set of winning the next 4 slams. Federer never had these confidence issues in his prime because of his supremer arrogance. Even if he lost, he believed that he was supposed to win. Perhaps this same arrogance prevented Federer from improving his game, but it certainly helped his consistency as he never had real confidence issues.