What amazes me, and others have said this in different ways, is that the whole top of the field have been great; my opinion of all of those guys has gone up. Today some riders were dropped repeatedly but kept coming back. The riders the coverage showed towards the end of the stage, the three in front and the 5 chasers, is the cream of the race. Only Porte was not on camera for pretty much the whole day, and he's doing very well too.
Sure, some are stronger than others, some have more support or better tactics, but how often do the top ten essentially race among themselves, mile on mile, as if the rest of the race had disappeared?
It's got to be the excellence of the course, the difficulty, which is producing this racing. Also the relative parity of the top ten, without a dominant rider with a powerful defensive-riding team.