Well while that may be true in cases of fresh test subjects, the circumstances at the end of a third week MTF after a 200km stage are almost impossible to research.No disagreement here about faster Alpe d'Huez times.
Yet there are zillion factors affecting the ups and downs in the ascent times, therefore it is next-to-impossible to know how much can be explained by one factor (doping) alone. I just don't see blood doping likely boosting FTP (and not certainly speed) by 10-15 % from the controlled blood doping research data, quite to the contrary.
I would think a lot of effects would cascade simply by increasing the fatigue resistance. And while I do think VO2 max and to a lesser extent FTP are a bit overrated, a higher oxygen carrying capacity would definitely be beneficial at every exercise intensity.
The one thing that's to be said about pro riders though is that they sorta simulate blood doping with altitude camps.