I am defining, with the help of Hugh Janus, a group of "Extremely Talented" riders that are a cut above those with enough "natural talent' to make it onto the start line at the TdF.
The Top 5%, the 95th percentile, comes out to 9 riders out of 180 staters.
Those top 5% have enough "Extreme" Natural Ability to win the TdF.
The Top 9 based on current Unibet odds are:
Contador, Schleck, Armstrong, Evans, Wiggins, Basso, Gesink, Valverde, and Menchov
I would argue that if all 9 rode clean - one of them would win the TdF.
Any of the other 171 riders with natural talent, even if doped, would not win IMO.
Of course, if any of the top 9 are doping things get complicated.
Maybe those top 9 can make a Gentleman's Agreement to ride clean?
And that brings us back to the original post - will Contador struggle to win.