Is it just Tour tradition that the team who currently has the yellow jersey should do the pacemaking? Why is it necessarily in the interest of the team?
Let's say that Floyd had finished at least 8 seconds slower than he did today in stage 11, or that our friend from Ag2r had finished at least 8 seconds faster. In either case, Dessel would have kept the yellow jersey, in all likelihood through the upcoming stages until the Alps.
Now, people are saying that it might have been better if Floyd had not taken the overall lead, because now his teammates will have to tire themselves to "defend the jersey" by chasing down breakaways, etc.
To me, given that Landis has said that "it only really matters if you wear yellow at the finish," it seems that Phonak's tactics have no reason to be any different than if Dessel had kept the yellow jersey. Whether Floyd was 8 seconds behind Dessel, or 8 seconds ahead, his team's aim should be the same: set their man up to be wearing yellow at the end of the race, whether he takes it now or later.
And maybe Phonak's aims/goals aren't any different currently than they would be if Dessel had kept the overall lead. It's just that now, Dessel's team doesn't have reason to chase down breakaways, whereas they would have had their man kept the overall lead. So now Phonak has no other teams to share the chasing load. But it seems as if Rabobank and other teams with high-placed possible winners also have reason to chase down breakaways, as much as does Phonak in these next few days.