They probably decided to put blue clay because they're tired of Nadal winning on Clay surfaces. So it gives an impression to guys like Federer, Djokovic and Murray that they are playing on HC so they think they can play their HC tactics to beat Nadal.
Nothing but visionnary images to the HC specialists.
Haha seriously, I think it will be different and I can't wait to see the results.
Pain is only temporary but victory is forever.