First of all, I know this is so cliche, but this is the NBA and even the bad teams can go on a run at any point in a game.
Secondly, the dubs are still learning how to win. They are not yet at the same level as the Spurs, Lakers, and Heat who can destroy an opposing team's spirit with a 20 point lead in the first half and basically cruise the rest of the game. The dubs will blow big leads every now and then, what's important is they now have the toughness to still win despite of.