I don't know more than a few riders who have won tours, but I'm amazed at how different they are. Is there any kind of stereotype for what a rider needs to excel in to be in a position to compete?
Team tactics aside, if you compare LA to AC, it seems they couldn't be more different. LA would win climb stages, and was dominant in the tt. AC is a good climber, but didn't win a single stage last year at the tdf iirc. Shleck seems to be similar in being pretty good at everything but not dominant.
Has cycling changed? Or have just not watched enough races?
When Contador won the '09 TDF, he dominated the TTs. He's also an absolutely explosive climber. The main reason he didn't win a stage last year was because he didn't have to. Schleck is a great climber and a terrible TTer, as is his brother. Sastre is a terrible TTer, as was Rasmussen (who would have won if he hadn't gotten caught), though I think both were fortunate in the weather patterns on the TT days. Basso isn't a terrible TTer, but won the Giro after Evans kind of crumbled, and Liquigas had by far the strongest contingent. Same with Nibali in the Vuelta.
Stronger TTers almost always have the edge... look at Lance, Contador, Menchov (and how he embarassed DiLuca at the Giro in the final TT despite falling), Valverde in the Vuelta, etc.