At the end of 5th set at 5-6 Nadal retired because of exhausted. He has 96% of form before match, I am pretty sure that in text mode he should have at least 50% at that moment. Long matches like Isner Mahut are impossible in 3D. And after Nadal retired what we have? 0-1 ret. in draw. where are 5 sets? bad bug, very bad.
I noticed that almost all matches on clay exhaust people to 10-20%, but in text mode never saw it. I think form decreasing should be more slow especially when it is low already, its crazy that people wastes last energy at full strenght like it is beginning. They should economy last energy like you did with tactics before match "-50% energy spending".