Consider this: from their inception in 1933 through 1971 the Steelers made the playoffs only once. Pittsburgh had only seven winning seasons, and managed only four seasons where they were two or more games above .500.
Then Dan Rooney took a bigger role in the organization, running the football operations in 1969 and finally formally being announced team president in 1975. He hired Chuck Noll and the team quickly went from annual cellar dwellers to perennial contenders. For those that lament the dark days of the Patriots, where the Steelers were prior to Dan Rooney taking on his role was was far worse. They went 25 years between playoff appearances. 25 years! From 1965-69 Pittsburgh's record was 14-53-3, finishing in last place in four out of five of those seasons.
Pittsburgh went 12-2 in 1975 and won their second consecutive Super Bowl. Rooney remained team president until 2002; during those years the Steelers were the class of the AFC and the best franchise in pro football over the last three decades of the 20th century.
More than anyone else, Dan Rooney was the reason for that turnaround. The Steelers' long term success was due to the leadership at the top of the organization. Rooney earned his place in the Pro Football Hall of Fame.
Rest in peace.