There is a serious question implied in your post that bears closer scrutiny I think: Is Nadal really hurting himself during the couple of hard court tournaments that he plays, or is it the result of his seriously heavy clay schedule, like a cumulative affect of the clay court season that manifests itself during the hard court swings?
Obviously there is no comparison, but I grew up playing on clay, satellites and futures in Europe...Going on hard courts was heaven after clay ! Clay is hard man...