Dan has such an uneven playing level sometimes. He was quite crap last week in Perth from all accounts and now he's in a QF of an ATP tournament this week. It's a bit like his US Open form - it always seems to come out of nowhere.
I don't think he really cared about the Hopman Cup, he tweeted a picture of a wooden spoon at the end of the week. It was just a way of getting plenty of high level tennis as a warm up for the serious stuff.
Overall though he is always going to be a bit inconsistent for at least two reasons. First of all he plays very aggressive tennis even though he doesn't have the height or natural power that he would ideally have for that style. To succeed at this level he is red lining things on a regular basis. On his good days he consistently hits the ball a few inches inside the line but on his bad days he is frequently out by a few inches. Secondly it is down to his personality, he is a big time player and thrives on the challenge of taking on good players in front of big crowds. Put him in an outside court against a journeyman in front of a handful of people and his motivation often drops. He once said something "What is the point of playing well if there are only 4 people watching?".