It might be. There are many posters who never post outside their favorite player's forum (understandable seeing as you need a thick skin to venture into GM territory), it's like their safe place from tards and haters. Given the hate Nadal gets in MTF, no doubt many of his fans will take shelter somewhere else, there are plenty of tennis forums on the internet.
Still, this thread seems to indicate that Del Potro, Tsonga and Nalbandian have more fans than Nadal on GM (people voting are presumably GMers) and Del Potro almost as many as Djokovic, yet there's far more discussion/posts about Nadal than these three players put together. I wonder why that is: are Nadal fans/tards just more vocal or?