Part of it will be the step up in standard but even accounting for that he has been pretty woeful with several DNFs and seemingly not being capable of doing much domestique work either (Edmonson on the other hand has done pretty well in his first year). In the British RR champs the course should have suited him but he was nowhere - from early on he was languishing in the main group with the domestic riders and top amateurs before chucking it. It wasn't that he was being outclassed by the likes of Cavendish, Millar and Stannard but also the likes of Wilkinson, House, Barker etc
It sometimes looks like an attitude problem but i've also read that he lost alot of weight (something like 9kg) in about 2 or 3 months on joining Sky. That would take a fair bit of dedication as he had already lost a fair chunk of weight the year before with Endura and reaped the benefits and had a good balance of power to weight for the short punchy climbs of the TofB and World Champs course. Perhaps he has lost too much weight too quickly and lost some power which taken away his strengths as a rider?