I'm willing to believe the explanation for this particular case, but I find the Cancellara video to be much more damning, and a pretty strong hint that mechanical doping has found its way into the highest levels of the sport:

https://www.youtube.com/watch?v=8Nd13ARuvVE

The way he just smokes everyone around him without changing his cadence, standing out of the saddle, or even changing the expression on his face seems at least a little suspicious.