I'm with
@400bhp - the evidence from what we're seeing is inconclusive. It is a relatively weak field and Landa has shown enough promise in the past to give his performance a veneer of credibility.
However...
The thing that really niggles is the fact that *every day* so far the race has finished well ahead of the fastest schedule - which is something we haven't seen for a few years. Even in 2012, Sky weren't tearing it up that much, were they? (Average speed of 2012 Tour was 1.6kmh slower than 2005, which is a significant time difference over 3000km.)
Also: stage 17 of the 2011 Vuelta, Froome looked half dead at the finish. Would like to see more visible signs of what racing like this is doing to Landa. Even Bertie showed signs of suffering today.
Plus, the biggest reason of all for being suspicious of Landa: he's riding for Astana, who shouldn't even be at the race.