It's ridiculous. Nadal can take huge cuts on almost every ball and put so much topspin on the ball that it almost never goes out. That is NOT tennis. There's a reason why a tennis court had boundaries - to prevent players from hitting the ball as hard as they can on every shot without the fear of hitting the ball outside of the boundaries. This is not baseball. Almost all of Nadal's balls landed in no matter how hard he hit the ball. He could hit ridiculous angles and the ball would still land inside the sidelines. The effect on the ball using polyester strings is really NO DIFFERENT than the effect on the ball using spaghetti strings - and they BANNED spaghetti strings back in the late-70's. So why haven't they banned poly strings yet? Eliminating poly strings would force players to use more variety, more strategy, differing pace and spins, attack the net more, and be more creative in keeping the ball in play rather than just taking huge swings and hitting the ball as hard as you can from the baseline on every single shot. It would also save a lot of recreational players who like to copy the pros from arm injuries and leaving the sport. Let's face it, poly strings have made playing against Nadal on clay almost unplayable and made watching pro tennis almost unwatchable because it's like watching a game of Pong (the video game). There's basically no variety and no strategy other than bludgeoning every ball with no fear of hitting out. If they came out with a technology which allowed Tiger Woods to hit a hole-in-one on every shot, don't you think they would immediately ban it as it would ruin the sport of golf? So why haven't they banned poly strings yet that is ruining the sport of tennis from what it used to be and supposed to be?