Top 10 off-the-court storylines of 2013

A look at the 10 developments that were among the most significant, most discussed and most prevalent off-court stories in tennis this year:

1. Grand Slam prize money increases

Tennis' four biggest tournaments increased their prize money substantially this year, bowing to sustained pressure from players for a greater share of the Slams' burgeoning revenues. The Australian and French Open went up 15-16 percent, while Wimbledon and the US Open increased by 30-40 percent. Larger increases have also been planned for upcoming years.

Politically, the concession represented a significant shift in the power balance between players and tournaments. The ATP had long tried to get the majors to provide a larger share, but late CEO Brad Drewett was more successful with the negotiations that had the big four players, particularly Roger Federer, lending their authority to the cause.

The increases played a big role in the new prize-money records set on both the men's and women's side. Rafael Nadal won $14.5 million and Williams $12.5 million for their efforts this past season.

2. Injuries

They didn't dominate the headlines, but injuries quietly took a toll on players as the season went on. Andy Murray missed the French Open and didn't play after the US Open because of a back injury that eventually required surgery. Maria Sharapova began having shoulder trouble in May and played only one event after Wimbledon. Roger Federer experienced back problems on and off throughout the season.

Serena Williams' Australian Open was derailed by not one but two injuries -- an ankle sprain in the first round and a back injury in the quarterfinals that was likely the result of trying to favor the ankle. Jo-Wilfried Tsonga began experiencing knee problems at Wimbledon for yet another year.

Not surprisingly, nearly every top player had a nagging problem at some point during the season, and there were scores of less high-profile players who missed time because of serious physical ailments.

Injuries took center stage on the third day of Wimbledon, when Victoria Azarenka and Tsonga were among seven players who withdrew or retired. Along with several upsets of players such as Nadal, Federer and Sharapova, “Wild Wednesday” was easily the most memorable day of the tennis year.

3. Coaching changes

The coaching carousel was in full swing this season. Federer parted ways with Paul Annacone, while Maria Sharapova went from Thomas Hogstedt to a short stint with Jimmy Connors to Sven Groeneveld. Sloane Stephens began working with Annacone on a part-time basis, while Caroline Wozniacki picked up Hogstedt. Jo-Wilfried Tsonga dropped Roger Rasheed, who went to Grigor Dimitrov's camp. Other players who switched include Richard Gasquet, Milos Raonic, Marin Cilic, Gilles Simon, Bernard Tomic, Angelique Kerber, Ana Ivanovic, Samantha Stosur, Eugenie Bouchard, Laura Robson, Heather Watson and Christina McHale -- and others -- but this should be enough to indicate that it was a busy year.

Former Grand Slam champions were a popular choice. After Ivan Lendl's highly successful pairing with Andy Murray last year, this year saw Connors,

Michael Chang (Kei Nishikori), Juan Carlos Ferrero (Nicolas Almagro), Goran Ivanisevic (Cilic) and Sergi Bruguera (Gasquet) all try coaching roles. Novak Djokovic made a surprise announcement this week that he was adding Boris Becker to his team, and even Federer had childhood idol Stefan Edberg training with him over the past few days.

4. Drug testing and match-fixing

Anti-doping was frequently in the headlines this year, starting with reverberations from the Lance Armstrong revelations in cycling. That helped prompt increased funding and testing in tennis, and with those increased tests came a renewed number of controversial cases. From Victor Troicki's missed test to Marin Cilic's glucose tablet mix-up to Nuria Llagostera Vives' two-year ban for methamphetamine, there was plenty to generate discussion and divide opinion.

As for the other dogging problem, a newspaper report before Wimbledon blasted the Tennis Integrity Unit for its handling of match-fixing issues. The unit still operates in much secrecy, but this year two Futures players received penalties for match-fixing, with a third hearing reportedly in the works.

5. Agency changes

As with coaches, the players weren't hesitant to change agencies, either. Former IMG clients Nadal and Federer both left the agency last year, and Nadal returned to the tour having established his own setup with longtime agent Carlos Costa. Federer and his longtime agent, Tony Godsick, took things a step further by announcing last week that they are starting their own agency, Team8, which has also signed Juan Martin del Potro and Dimitrov. Andy Murray partnered with his agency, XIX Entertainment, and others to begin 77, with some of it now reportedly being handled by the Lagardere group. And IMG was sold to the William Morris agency, with private equity backing.

It's a long way from the early days of Open tennis, when IMG and ProServ were the only game in town.

6. Anniversaries

It was quite a year for anniversaries, particularly those related to the professionalization of the game. This year marked 45 years since Open tennis began in 1968, and 40 years since the 1973 ATP boycott of Wimbledon, the formation of the WTA, the Battle of the Sexes and computer rankings. Others include 25 years since Steffi Graf's Golden Grand Slam, 10 years since Roger Federer's first Grand Slam and five years since the epic 2008 Wimbledon final between Federer and Nadal.

Some provided extra significance for this season's accomplishments. Serena Williams' French Open victory came 10 years after she completed the Serena Slam. It was also Williams one-year anniversary of losing her only first-round Grand Slam match.

7. Calendar shifts

The WTA increased its move into Southeast Asia by awarding the year-end championships to Singapore and announcing a number of new events in the region, which will host about a dozen tournaments next year. Two ATP events in the U.S., San Jose and Los Angeles, relocated to South American locales in Rio de Janeiro and Bogota, Colombia, respectively.

The grass season is also being reconfigured for the extra week between the French Open and Wimbledon that will be introduced in two years. ATP tournaments at Queen's and Halle are to become 500-level events, and the current clay-court event in Stuttgart will switch surfaces and dates. The WTA will add a new grass-court event in Nottingham.

8. New heads appointed

The search for a new ATP chief remained ongoing when Drewett passed away, and after several months, Chris Kermode was announced as the new leader of the men's tour. Kermode was the tournament director of Queen's and the managing director of the Tour Finals, and he had an endorsement from Andy Murray.

There were also some changes among the national federations. Craig Tiley was made the head of Tennis Australia in addition to being the tournament director of the Australian Open, while Tennis Canada head Michael Downey was chosen as the new chief executive of Britain's Lawn Tennis Association.

Exits included Andre Silva, the ATP chief player officer who has joined the new Team8 agency, and WTA communications VP Andrew Walker.

9. Courageous comebacks

Alisa Kleybanova was named WTA Comeback Player of the Year. She returned to the tour two years after revealing she had Hodgkin's lymphoma. That was the same diagnosis received by doubles player Ross Hutchins, who underwent six months of chemotherapy this year and plans to return at the beginning of next season.

10. Court decisions

The Tennis Channel continued its battle with cable giant Comcast over its placement on a subscription sports tier. The channel won decisively at the FCC level but lost a subsequent D.C. Circuit Court ruling and was not granted an appeal. It has now asked for a review of the decision from the Supreme Court.