(AP Photo/Don Wright)

When the economic crisis of the 1970s hit, fans rallied around sport like a deep-ocean buoy. That decade, no city won like Pittsburgh and the region was branded “The City of Champions.”

However, since they were bounced in the first round of the 2011 playoffs, things have been disastrous for the Pittsburgh Steelers. They hold a 602-540 all-time record and the most Super Bowl championships of any team in NFL history (6), but haven’t eclipsed a .500 record in three years, are in one of the worst stretches in franchise history, and are coming off a 2013 campaign that marked the first time in nearly two decades the black and yellow missed the playoffs in subsequent seasons. Their stretch has felt more lurid than mirage, and it doesn’t appear 2014 will bring the turnaround Steeler fans desire.

What’s perhaps more intriguing and noteworthy is how sensational their defense had been during non-playoff seasons prior to 2013. Behind Dick LeBeau’s matrix of a defense highlighted by the zone blitz he created in the 1980s, prior to last season, Pittsburgh hadn’t fallen out of the top 10 in total defense since 1999. The Steelers have led the league in fewest yards allowed five times since LeBeau took over as defensive coordinator in 2004. Last season, they finished No. 13 overall, the lowest ranking since 1992.

Since 2000, the Steelers have made the playoffs eight times. In those eight seasons, their red zone defense has allowed touchdowns 47.35 percent of the time. However, in the last two seasons they’ve given up scores on 53.3 percent of opponents’ opportunities. Their 3.8 weighted defense percentage, an adjustment marginalizing performances in the first few games of the season that aren’t as important as the season progresses, fell into the lowest tier of the league in 2013.

An inconsistent pass rush, an inability to produce turnovers, and one of the worst rush defenses—no. 21 overall, to be precise—in Pittsburgh history marred last season. LeBeau’s squad fell out of the top 10 rushing defenses for the first time since 2003. Their Defensive SRS, which estimates the amount of points over average prevented by their defense, came out negative for the first time since 2002 and their margin of victory hadn’t been as low (0.6) since 2003.

In their last six playoff appearances, Pittsburgh has given up an average of 15.2 points per game — ranking in the top five overall in that category in every season—and gave up no more than 1,597 rushing yards in a season. Last season they have up 23.1 points per game—no. 14 overall—and 1,849 rushing yards.

Add that Pittsburgh also has the toughest strength of schedule of any in the AFC North (.469 opponents’ winning percentage) this season to the equation, in one the four toughest divisions in football, and chances look even more barren.

The point is this: Pittsburgh has been sustained by a steel-plated defense for nearly every season since the new millennium, it’s been the team moniker since “Mean Joe” Green, L.C. Greenwood, Ernie Holmes and Dwight White created a juggernaut in the 1970s. If they couldn’t make the postseason with one of league’s five best defenses, as was the case in 2012 and 2009, how can they do it behind one that finished outside of the top 12 a season ago?

They are in the midst of one of just three consecutive non-winning seasons since 1970 and will need remarkable improvements on the defensive side of the ball to reach the playoffs in 2014.

Adding an inside linebacker and defensive lineman in the first two rounds of the draft will help, as will Mike Mitchell to play alongside Troy Polamalu at safety, but as the Pittsburgh Post-Gazette noted, through the first two weeks of the preseason they’ve given up an average of 160.5 rushing yards per game.

It remains to be seen, but Pittsburgh has a lot to improve this year if they hope to win nine games and break through to the postseason.

Josh Planos has had his work featured at the Wall Street Journal, Chicago Tribune’s RedEye Chicago, Rivals, Denver Post, CBS Sports Radio, Fox Sports Radio, and ESPN Radio, and is currently a columnist for the ESPN TrueHoop Network and The Cauldron. He loves interacting with readers via Twitter (@JPlanos).