It is not altogether clear why—inevitably, there is a number of contributing factors—but one major area in which Pittsburgh Steelers quarterback Ben Roethlisberger struggled, at least during the early portions of the 2017 season, was in the deep passing game.
Roethlisberger’s success rate in completing passes when he threw the ball far down the field really lagged in the early games, but it did improve as the year went on. The Steelers also played more at home in the second half of the season and into the playoffs, and Pro Football Focus points out that his numbers greatly favor his home performance on deep passes.