It doesn't really matter how much time you spend practising, Contador is SO much *quicker* that Schleck. Where Schleck is awesome is mountains. The wya he can ride in mountains (easily one of the top 2 mountain climbers of the lot) would indicate, usually, a useless time trial. And if he had been practising his time trialling, one would have expected him to at least show some of this on the prologue - where he lost 42 seconds to a (for him) poor Contador performance, coming in 122nd, and behind the likes of Rodriguez (and 12 seconds behind Frank)
The question for me is whether Schleck/Menchov (as both are, IMO, far superior in the harder mountains, especially considering Evans' fitness after completing the Giro won't be as high) can gain enough time on Evans so he can afford to drop a min in the ITT (which is the most realistically I can see Evans getting - his TTing isn't quite as good now as it was a few years ago as he has improved the ability to attack others or shallower climbs)
For me, a top 5 (as I said previously) for Evans would be a massive achievement, as I can't see him being able to stick with a group of, say, Conti/Schleck/Menchov/Wiggo/Basso/Kreuzeiger in the steeper moutains, if only because of lack of team strength).