It is unrealistic to expect Federer to win every event, but to compare this one loss to a time when he was in a long, by his standards, down period is unfair. He was competitive in the 7-6 (1), 6-4, 3-6, 6-3 loss, so it wasn't like he got blown out of the water.
Plus, Federer did a lot more damage to himself than Berdych was doing, though that is not to take away from Berdych because he did what he had to do in order to win.
Sometimes a loss is a loss, nothing more, nothing less. Federer does not have to completely overhaul his game after losing this one match. He is still the same player, after all, who has won six tournaments this year, including the Wimbledon. He is doing okay, even by his lofty standards.
So what does Federer need to take away from this loss?
First and foremost, he just needs to maintain his focus. Within that same ESPN article, Howard points out that Federer gave up his serve two times in the first set, which is almost unheard of for him.
That kind of sloppiness can be attributed to a one-time bad game or a sign of fatigue. As much as I am championing Federer for the great season he has had, there can be instances where he will need to take a little extra time off in between events to recharge his batteries.
This loss, while it stings, can be the slap in the face that Federer needs for the remainder of the year. He is not going to fall apart and retire, a la Andy Roddick, so don't overreact to the loss.
Recognize that he is a superstar capable of playing at the highest levels on any given day. It just didn't happen on this one day.