We've all seen bad officiating in the NBA — where the crew in charge doesn't seem to know what it's doing, where fouls appear to be called randomly, traveling calls are obviously wrong (per video), and phantom ticky-tack whistles on one end are matched by no-calls for outright muggings on the other — and then vice versa. When that happens in a game, BOTH teams suffer — because despite what fans often believe, bad refs are equal opportunity abusers. They mess things up all over the place.
Conventional wisdom has it that the mistakes refs make tend to even out over the course of a game.