Low-Probability Disaster of the Day, Exosphere Edition

From Andy Pazstor:

Pentagon brass, satellite industry executives and NASA leaders for years have publicly expressed concern about the dangers of orbital debris. But the odds of a direct hit between satellites were considered so small as to be basically unthinkable.

Is there a way of distinguishing, ex post, between (a) the ex ante probabilities having been wrong, and (b) the collision having been genuinely improbable? I’m going with (a).