Discovery has this down pat. Ride fast enough when needed to control the race, but not so fast as to waste energy.
I beleive Bob Roll made an insightfull comment this week (im not a big Bobki fan but ill give him credit here). He stated that the Discovery tactics inflict a sort of amnisia on the field. They forget why they are at the TDF and just start to ride along.
Even the biggest Lance fan has to admit there have been but a few "cruch time" moments this year, although he has risen to the occasion every time.