Coverage sacks are and will continue to be a thing in the NFL.
What do you think has a higher probability of success in the NFL? Coverage sacks or pressure on the QB? According to the vast majority of experts it's the later, by far. You can only last so long in coverage but a good pass rush makes all DB's look good. It would seem like that last drive by the Steelers, after a great O drive and only a minute left, would have convinced anyone that the R's need a play maker on D, a pass rushing play maker.