Report Card: Djokovic soars in London

Novak Djokovic outlasted Roger Federer in two thrilling sets to win the title at the ATP World Tour Finals. (Kirsty Wigglesworth/AP)

LONDON -- The ATP season is officially over, and as the last piece of blue and white confetti fell in the O2 Arena on Monday, Novak Djokovic was the last man standing. Djokovic consolidated his year-end No. 1 ranking with a mind-bending victory that has contortionists all over the globe picking up a racket.

Here are the final marks for the final week of the ATP season, which wrapped up at the World Tour Finals. Final, final, final. Get it? We're finally done with ATP events.

Novak Djokovic: A-plus. The No. 1 went undefeated for the week, beating Roger Federer, Juan Martin del Potro, Tomas Berdych, Andy Murray and Jo-Wilfried Tsonga to pocket $1.76 million and bookend his year with two big titles: the Australian Open in January and now the World Tour Finals. Watching Djokovic through the week, I marveled at just how far he's come. This is a guy who exploded onto the scene in 2011 despite a reputation for being mentally and physically fragile, soft in all the wrong ways. He would check out of matches, mentally throwing in the towel when things got tough and shrugging fatalistically as if to say, "Oh, well. The tennis gods are against me and it's just not my day."

Maybe it's just habit, but I still look for signs of Beta-Nole when he falls behind in matches, but I haven't seen him around these parts in a long, long time. The guy looks physically unbreakable these days, even as he undertakes leg-snapping starts and stops, and mentally there's absolutely no quit. He truly believes in his talent and skill -- and why shouldn't he after backing up his historic 2011 with another No. 1 season? That belief translates into laser focus on the court. So ... xan he do it again in 2013?

Roger Federer: A-minus. The scoreboard may show a straight-set defeat to Djokovic in the final, but it belies the fact that Federer lost by the slimmest of margins. Overall, it was a good week for Federer, who bounced back from disappointing losses in Shanghai (Murray in semis) and Basel (Del Potro in final) to make his third straight year-end final in London. Federer's most important victory came in the semifinals when he rallied from 2-4 down to defeat Murray in straight sets, snapping a two-match losing skid to the Scot. We'll see if the three-set loss to Del Potro in what was a dead rubber for Federer comes back to haunt him next year. That win propelled DelPo into the semifinals and allowed him to end his year with two straight wins over Federer on indoor hard courts, a tremendous confidence booster given Federer's dominance on the surface. Victories like that can create a monster.

Andy Murray: B. Well, we can't really argue who the No. 3 is, right? Murray finished his year with losses to the two men ahead of him in the rankings -- Djokovic and Federer -- and couldn't summon his best tennis when he needed it most, especially against Federer in the semifinals. Murray deserved more from the British crowd, which seemed lukewarm in its "hero's welcome" all week, but then again, the British crowd probably deserved more from him. He's yet to play his best at the World Tour Finals, but at least this time he was able to walk away from the event with his body intact.

Juan Martin del Potro beat Roger Federer in group play to reach the semis, and looks to be regaining top form heading into 2013. (Julian Finney/Getty Images)

Juan Martin del Potro: B-plus. Is the Big Man back? We'll have to wait a couple of months to see, but Del Potro was in good spirits all week. Humble and soft-spoken, Del Potro is usually one to defer to the talents of his peers, sidestepping any comparisons of his level and expectations with the Big Four. But I noticed a change in tenor at the World Tour Finals, as his victory against Federer and 2009-ish level against Djokovic -- at least for a set -- seem to have unlocked his belief. Like muscle memory, the Argentine has remembered how he needs to play against the top guys and, more important, he's remembered that he can play with the top guys. Watch out, 2013. If I had to wager, I'd say DelPo is back.

David Ferrer: B. Tough luck for Daveed that he went 2-1 in pool play but failed to qualify, especially given he beat Del Potro. Ferrer took care of business as best he could, downing Del Potro and Janko Tipsarevic, but he had no answers against Federer, falling to 0-14 vs. the Swiss.

Jo-Wilfried Tsonga: C-minus. Was Tsonga even at the World Tour Finals? I can barely remember. He went 0-3 in the tougher Group A, winning just one set, and he just never looked like he wanted to be there or that he believed he could win a match. New coach Roger Rasheed has a lot of work to do during the offseason.

Janko Tipsarevic: D-plus. Under the weather before and during the tournament, Tipsarevic admitted he came into London with very little practice and couldn't play his best. "It's sad to say, but this is the best I can do right now," he said after a 6-0, 6-4 loss to Del Potro. "I'm playing horrible. I'm playing worse than horrible. I'm playing the worst tennis that I played in a long time. But I'm on court, behaving good, not throwing my racket, giving my best."

I'm not sure fans were shelling out upwards of $80 to see a top-ranked player behave well and not throw his racket. For a guy who savored his first London experience last year as an alternate when Murray withdrew with injury, Tipsarevic should have ceded the stage to an alternate. He sarcastically bragged that he was proud to make it past an hour in his first two matches. Trust me, Janko, that wasn't an hour that anyone particularly enjoyed.

Tomas Berdych: B-minus. I expected more from Berdych, which was probably unfair given he was drawn into the Group of Death. He ended his season with a straight-set loss to Djokovic, a three-set loss to Murray and a three-set win over Tsonga. Nothing to be disappointed about, but definitely a missed opportunity. On to the Davis Cup final vs. Spain for Berdych.

Marcel Granollers and Marc Lopez: A-plus. No doubles team was more fun to watch than Granollers and Lopez, who edged Mahesh Bhupathi and Rohan Bopanna 7-5, 3-6, 10-3 to become the first Spanish duo to win the World Tour Finals. Their win over Bob and Mike Bryan in the first round of pool play was my second favorite match of the week -- the first being the Djokovic-Federer final -- as the exuberant team, led by the 30-year-old Lopez, lobbed and poached and chased down everything. Lopez, who has served as Rafael Nadal's hitting partner at various times over the years, was in tears after the win, and the beaming smile plastered on his face isn't going away anytime soon. The confident pair will surely play a key role in the Davis Cup final this weekend.

Mahesh Bhupathi and Rohan Bopanna: B-plus. They lost the final but, boy, avenging their Shanghai loss to Leander Paes and Radek Stepanek had to feel good after a year in which they've been embroiled in controversy with the All India Tennis Association.

Jonny Marray and Freddie Nielsen: A. In their last tournament together, the Wonder Boys of Wimbledon continued to put on a show, qualifying for the semifinals with wins over Bhupathi/Bopanna and No. 2 seeds Max Mirnyi and Daniel Nestor. It's a real shame they're breaking up. Such a fun team to watch.

Mike and Bob Bryan: D-plus. The duo's golden year ended with a tough week, as they failed to reach the semifinals for the first time since 2006. No matter, though, as they walked away with the year-end No. 1 trophy and once again dominated the voting for ATP Fan Favorite doubles team.

Round-robin format: B-minus. I go back and forth on this. On the one hand, it's great for the paying fans, who can count on at least three matches from their favorite players. And it must be nice for the players to know that they can fly their friends and families to the tournament knowing that they can plan an extended stay. On the other hand, I don't love the format in the early rounds of play, where, really, a loss isn't the end of the world, and the tension and drama aren't what they could be. In the end it worked out well this year, however, with all of the third-round matches carrying some qualification significance. No one likes a day of meaningless matches.

London as host: B-minus. You can't argue with the capacity crowds who have no problem dropping a good chunk of change in exchange for two matches -- one singles, one doubles -- per session. Financially, this tournament is a boondoggle, and in many ways London is a perfect host. But the O2 Arena still leaves me cold in its corporate soullessness. Even when it's full, it feels empty. The complaints, of course, are pointless now, as the ATP has opted to keep the year-end finals in London through 2015, but I do find myself looking forward to seeing what this tournament would look like somewhere else.

Brad Drewett: D

reportedly abstained