I wasn't talking since the last year. I am talking about the last 10.Since last year, the AO is faster than the USO. The AO has been fast enough for Nadal to hit through. Faster than the USO.
I am not sure if the AO is faster than USO. I heard the same arguments in 2010 when Nadal won USO, about how all of a sudden it was slower than just a year before. I don't buy it. To me, there was no difference between USO in 2009 and 2010. It seems like the surface gets magically slower when Nadal wins.