Atp was struggling with Federer dominating fast playing. so they slowed everything down (surfaces and balls) to make it less competitive for Federer and give a chance to the rest. This is how Nadal and Djokovic stood a chance. The fact that Djokovic is at 24 slams and Nadal at 22 is also thanks to that. People forget that. It's funny now to see Djokovic asking for faster balls. He should just shut up and play the game. He should be happy with his career and all