Federer has been aggressive and is coming to net more than he's ever done even at Wimbledon. I think he's finally realized - 1. grinding on clay is not efficient and is best left to bumrooters who can do nothing else. 2. he has to sharpen up his netgame on clay to get ready for Nadal. He also did a lot of SV in Hamburg. 3. GOAT's come to net. So basically, in the QF's of a slam which he's supposed to be under a lot of pressure to win, Fed is practicing tactics and tuning up his game.