Obviously, average speed doesn't have anything to do with the GC winners... How big a percentage of the time do you think they are in front of the field, driving the pace?
Besides that, you don't have to convince me that it was an impressive win. No doubt about that, but it certainly has nothing to do with average speed.
I think average speed benefits from shorter stages and aerodynamic evolution.
Yeah I mostly agree. However, it does seem like the great champions often win very fast Tours. Certainty there is a correlation of ability and being able to finish towards the front of a super fast moving peloton day in and day out. Yes, the course wasn't super hard. Yes, they raced hard just about every day however Ving had to go that speed and still not pay the price with a bad day. Everyone else in the race had bad days, the overall race speed had to contribute to that.
Plus, while we're talking about conditions nobody mentions the heat. Surely the heat wore down many riders. Not Ving or his teammates but it definitely hurt the others.
So sure, race speed isn't the greatest sign of a big win but you can't ignore it either.