Take some of the great past champions----Anquetil, Merckx, Hinault, Fignon, LeMond for example---they all contended/won/made the podium in their very first TdF.
It wasn't until EPO and blood transfusing hit the scene that former pack fodder like Lance and Mig went from DNFs or 80-something finishes, to the top step in consecutive years, while dropping skinny Columbian mountain goats on the climbs.
Froome was pack fodder until he joined Sky.
U.S. guys know the old saying, if it looks, walks and quacks like a duck......