Survival of the fittest is a basic premise of the natural selection mechanism. Thus, if the market mechanism works well, the productivity of successful and surviving firms should be higher than that of failing and hence exiting firms, at least on the average.
In this figure, the shaded areas show cases where the productivity of failing and thus exiting firms is higher than that of surviving firms, which is an anomaly. In fact, the shaded areas are rather exceptional most of the time.