Before the match, Djokovic had been off his game all week—partially due to an injured shoulder. He fell a set behind to Gael Monfils in the quarterfinals, and was down a break in the first set against Tomas Berdych before rallying to win the set 7-5 (Berdych eventually retired with a shoulder injury).
Djokovic wasn't truly beaten by Murray. Murray did not actually play very well, and it was only because of truly sub-par play from Nole, as well as an injured shoulder, that the Scot took home the title.
It is clear that Djokovic is exhausted and was running out of gas this week. One reason for this is fairly obvious: Novak has found himself going deep into every tournament. Eventually, these days and matches begin to add up.
Also, "the Djoker" has become an overnight international superstar. Every pair of eyes was going to watch his streak in the US Open. However, he has finally lost. For the first time this year, he will go into a tournament having already lost on that surface.
Djokovic is not going into the Open under-the-radar by any means. He is still the favorite to take home the trophy, but entering the tournament off a loss does take some attention away from the Serb.
Djokovic now has a week to recover, both physically and mentally, for the US Open. His shoulder injury doesn't look too serious, but he does need to get some rest.
Most losses show a chink in the losers' armor, but this loss surely does not. Nole was injured, so his serves were never in the triple-digits, and his ground-strokes were off as well. No player has ever truly found a weakness in a totally healthy Djokovic.
Of course, the bum shoulder will be an issue, but he may have simply pulled out of Sunday's match in order not to aggravate a minor injury. Instead of finishing a match he knew he could not win, he decided to retire and keep his shoulder pain at a minimum.
Last weekend, viewers could easily notice that Novak just wanted it all to end. Now it has. So all that's left on the Serb's agenda is to go to New York and take care of business. He'll be more relaxed, less will be on the line, and he will probably play more freely.
Andy Murray, the only other member of the big four having a good summer, seems to have been gaining on Djokovic as far being the favorite. But if the shoulder injury is not too serious, Djokovic knows that he is the clear favorite, and his confidence won't take a hit.
Everything does revolve around the gravity of Djokovic's injury, but for now, Nole may have gained a lot from just one single loss.