I'm a complete ingénue on this sort of stuff, so please forgive me for anything I say which is stating the bleeding obvious or has already been posted.
It looks to me like Sky have got the numbers for everything; how much power each of their riders can put out, and for how long. Combine that with the knowledge of the gradient on each climb and the power output required to get up it, and they can plan precisely who goes on the front and for how far and at what pace such that the desired number of riders reach the finish line as fast as possible having expended their last calorie of available energy (whilst leaving some in the tank for tomorrow).
Knowing all that they ride the race at their pre-determined pace secure in the knowledge that anyone who attacks will be reeled in having burnt too much energy to recover fully. As long as everyone in the team toes the party line, they get a result. Until, of course, the unexpected happens ...
Very very methodical. Very Brailsford.