The main problem for Sky this year is that they've been forced to spread their resources across two fronts (Wiggins' Giro bid & Froome's TdF). The fact that Henao & Uran did the Giro left the squad looking a bit thin by the time this race came around and there was always the risk that if Porte got dropped Froome would be isolated. When you think of the super-domestiques that Wiggins had at his disposal last year (Froome, Rogers, Porte) this race was never going to be as easily controlled this year.
I thought Froome was as impressive on Sunday as he was in taking the jersey the day before and I also think it's highly likely that he'll face this scenario again once or twice when we hit the Alps. Tomorrow's time trial is a big one for Froome because I honestly think he could do with taking a bit more time out of Valverde & Quintana before we're back in the mountains as Movistar have looked very strong so far.