Tennis aims to improve consistency of balls

Yellow felt and a rubber core. A tennis ball seems so simple. But the reality is more complicated, at least on the pro tours where manufacturers can make balls that fit into a range of specifications.

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And in recent years, with players forced to adjust to different balls at so many tournaments, they have begun complaining about the consistency and quality of the balls as never before.

Novak Djokovic spoke out. So did Rafael Nadal, Taylor Fritz, Daniil Medvedev, Stan Wawrinka and Andrey Rublev.

The varying balls not only harmed the quality of play, according to players and coaches, but the athletes blamed them for the increase in shoulder, elbow and, especially, wrist injuries.

"The quality of even the best balls has come down in the last few years," said Craig Boynton, who coached Hubert Hurkacz. "They should not just be picking the ball that will pay the most money to be associated with a tournament, but what is the actual best ball."

Lower-quality balls can feel like rocks early in a game then "get fluffed up like little kittens" after a few games, he added. When that happens, "players trying to muscle the ball more" by swinging with more force to make up for what the ball is lacking can get injured.