Eh, I beg to differ re dubs vs singles. I can personally attest to absurdly streaky singles play also.
I think it comes down to inconsistent execution, in both singles and dubs. Let's face it, at the rec level, on any given shot and point, there is some probability we are going to mess up. Sometimes we go on a 'lucky' streak, where we generally avoid messing up for a few points and games, and then sometimes the opposite. Like flipping a coin - flip a coin enough times, and you'll have streaks of heads and streaks of tails.
Of course playing style has something to do with it. Conservative players tend to make less errors and therefore are less prone to streaks, unless the streak is a result of the opponent's play. Aggressive players are great at making their own streaks!