I think that there are so many factors. The olympics will have curtailed any specific preparation, and the tdf win would take a degree of importance away too.
The Sky team seemed to lack the nous of a G or a Stannard or Rowe to manage thd situation on the day. Missinv the break was key. I think that stayinv in contention until the tt was the card that sky were playjng.
As for multiple GT wins in a season, in a non olympic year with specific preparation i think its doable, i think it was a team issue this year. Giro Vuelta double would be the least tough option, but with the tdf as the main target, that is unlikely. Unless they allow landa or g to go for it.