1. Australian Open- "The first of the Grand Slam troika is now played on the slowest surface of any large tournament. As Martina Navratilova described it, "The (Australian Open) court plays much slower than a clay court, plus the balls (switched to Wilson all-courts this year) fluff up and play slow."
2. French Open - "The percentage of points won by winning shots, as opposed to errors, at the French Open is 34%, barely less than the US Open figure and roughly a third more than at Aussie and Wimbledon." "One wild card is the introduction of new balls last year from sponsor Babolat. Although the Babolat balls were built to the same specifications as the old Dunlops that had been used for many years, they are livelier. This helps servers and might well have contributed to Roger Federer's good run last year, ending Djokovic's winning streak and pushing Nadal. We'll see if they tweak the balls going into 2012."
3. Wimbledon - "Is Wimbledon fast, slow, low-bouncing and slick or hard? Yes. Depends on where the ball lands and when during the tournament, and whether the tournament is rain-soaked or sun-baked. At the beginning each year, Wimbledon is covered with lush grass that slows down the ball, but helps sliced serves, backhands and approach shots stay relatively low. By the tournament's champinoship final, grass still covers the service box, slowing down serves, but the baseline looks like cracked concrete of a playground basketball court."
"Wimbledon switched to thicker grass, packed the dirt harder (making the ball bounce higher), and switched to what are, apparently, larger balls that slow down as they travel through the air, and bounce higher and more slowly. The tournament is closed mouth about the balls, but the Slazengers reportedly have 6% greater cross-sectional area. Despite claims that the court was only slowed down 10%, the difference is far more dramatic. A BBC video shows how dramatic the impact the combination of all these changes has been -- as well as showing that play has been slowed down between 2003 and 2008 (contrary to claims that the courts have not been further slowed since 2001).
BBC overlaid two serves by Roger Federer, one in 2003, the other in 2008, both at 126 MPH on a similar line of flight. The 2008 serve goes 9 mph hour slower, after the bounce, than the 2003 serve, or 20% slower. The ball also bounces perhaps a foot higher. This is a tremendous advantage for the returner: The ball is slower, arrives later and sits up. That's why some cynics say that Wimbledon has turned into a green, clay court tournament."
4. U.S. Open - "The U.S. Open is the, only substantial tennis tournament played on a fast surface. Per the ITF standard, the U.S. Open is rated a "40", which used to be medium fast, compared to a 34 for the Aussie. Also, the U.S. open uses lighter Wilson pro tennis balls, which play quicker than the Pro Pen's used on the ATP circuit, or balls at the other majors. Plus, the ball bounces lower than at the Aussie and French. Let's do a quick run down of other, significant tournaments to show how the hard court-clay court paradigm no longer holds up: Miami is one of the slowest playing sites on the ATP Tour playing, as Fed describes it, "like a clay-court you without the sliding", while Madrid is on clay, but because of the 2,000 foot altitude plays pretty fast. Witness the near rebellion by the Spanish Davis Cup team forcing organizers to move Davis Cup matches out of Madrid to a site that favored the "clay court players". BNP Indian Wells moved to its own custom-blend of Plexipave, slick and plastic feeling but with deep crevices; as Navratilova describes it, "You can't come to the net. The court is so slow your opponent can be sitting on the sideline and have time to get up and pass off your volley." Possibly an exaggeration. The year-end ATP World Cup uses a Plexipave surface similar to the U.S. Open, but since it is layed on carpet indoors, it is slow, but low bouncing. There, you see aggressive attacking play and a wide variety of players winning matches from Nikolay Davydenko, to David Ferrer to Juan Martin del Potro. So, the old paradigm is dead. Today's reality is a homogenization of tennis that reduces the variety of play and leads to clay-court-style baseline grinding dominating throughout the year, out side exceptions at London's AWC, Paris and a few sites on the Asian circuit."