Rafa has played Wimbledon 6 of the past 7 years. In those 6 years he reached the final 5 times and won twice. The only current player with a better Wimbledon record is Federer.
For that reason I hope Andy gets Federer in the semis. I don't want Andy playing Rafa. Do I think Andy can beat Rafa? Yes. However, I still prefer him to be in Roger's half.
I'd be more interested in looking at Nadal's current results on grass, Wimbledon in particular than looking a bit far back. Nole, for example, isn't a great grass courter and Rosol basically came out from nowhere. Nadal took beatings to both in 2011 and 2012.
Also, when it comes to Federer vs Nadal, it almost always comes down to match up issue only, so other than WTF, where the surface is relatively fast and the conditions are controlled, Nadal will always get a win over Federer. So I am not sure how much you can bank on his performance on grass thus far based on the fact that, he never had to play any true grass courter in those years other than Federer. Granted, he had played Murray 3 times but Andy was still coming into in his own term being fairly young on tour; on top of that, he had his own mental issues that needed to sort out first, so it didn't matter who he faced on the other side of the net be it Nadal or Nole or Federer. He lost to all of them multiple times in Majors.