I think poj is actually a very smart rider, knows exactly when to dig and reads races very well. Got caught out last year at tdf in the wind but attacked when he was strong and sat when he realised there was no point. Same at vuelta year before and same yesterday. Looked like he was riding within himself and smartly to win the stage.
That and he hasn't got a team who can be there for him means he has to be clever to win, he's not really doing much different than a sky or jumbo train just the guys in front of him aren't his teammates.