I'm glad others are mentioning how underrated Noll is/was, I just didn't want to be the one to bring it up. Remember that even after the dynasty ended, he led the 1984 Steelers to the AFC Championship game with Mark Malone and Frank Pollard (as well as an aging John Stallworth) leading the way. And that was the only team all year to beat the 49ers, so who knows, maybe if they had made the Super Bowl, they could have at least stayed within 20 of that Niners team.
He also led them on a bit of an improbable run in 1989, rebounding from being outscored 91-10 in their first two games against Cleveland and Cincy, to make the playoffs, upset Houston, and nearly knocked off Denver with Bubby Brister and a backfield tandem of Tim Worley and Merrill Hoge. Who knows? If that team beats Denver, maybe they could have held that Niners team under 50.
They never recaptured the 70s, but even at the twilight of his career he was able to extract some improbable runs out of undermanned teams. Yes, if he fell to me in the all-time draft, Chuck Noll would have been my selection over Joe Gibbs.
I do have to add that right now, I love everything about the way Mike Tomlin handles that team. And when Bill Cowher is probably considered the 3rd best of your team's last 3 head coaches, your team has likely had a pretty good run.