“Defense wins championships.”

It’s a dated platitude that has no place in modern football analysis, but it’s rooted in the belief that elite defenses shut down elite offenses. It’s an idiom that once embodied the Steelers. The Steel Curtain of the 1970s is obvious, but even their Super Bowl runs in 2005 and 2008 came on the backs of top-five defenses in terms of points per drive against.

This year’s Pittsburgh team is on a path to once and for all prove the cliche to be false with an offense that has dropped 30-plus points in six straight games. But even if defense doesn’t necessarily win championships, a lack of it can certainly cost you a championship. With glaring holes at every level of the defense and a stacked deck against them, the Steelers can’t be considered the favorite in the AFC.

Let’s start with the good. The Steelers can score on anybody. They proved that Sunday after they put on a show against the best defense we’ve graded out in the past nine seasons. And it was far from a fluke. Ben Roethlisberger is grading out on par with the likes of Tom Brady, Cam Newton and Carson Palmer on a per snap basis and it’s truly a shame his injury will cost him deserved MVP consideration.

If you still think there is a better receiver in the NFL after Antonio Brown torched multiple-time PFF All-Pro cornerback Chris Harris for 14 catches and 164 yards then there is no changing your mind. Martavis Bryant is one of the best deep threats in the league with the 14th most yards on passes over 20 yards downfield despite more drops than anyone on deep targets except Ted Ginn Jr.. And their No. 3 receiver Markus Wheaton put up over 200 yards against the Legion of Boom. No team in the league can match up with Pittsburgh’s weapons.

The issue come playoff time isn’t the offense though, it’s their defense. Traditional stats don’t tell the whole story with the Pittsburgh defense. In terms of points per game against, they are only 0.6 behind the undefeated Panthers. When it comes to yards per game they drop behind Jacksonville at 24th overall. And in PFF’s play-by-play grading, they have our 25th overall defense and the fifth-worst pass defense in the entire NFL.

There is a reason that in recent weeks the Steelers gave up 27 points to a lowly Broncos offense, 35 points to the Raiders and 39 points to the Seahawks. Their secondary is far from championship caliber. They wisely relegated cornerback Antwon Blake to sub-packages in Week 13, but he’s still one of the biggest liabilities in the league. The fourth-year player has already ceded 998 yards in coverage this season, the ninth-highest total in the past nine seasons. Then there’s the issue of their linebackers, Lawrence Timmons and Ryan Shazier whose 21 combined missed tackles in coverage is the most of any duo in the league. Timmons’s play has been especially concerning as he currently sits among the bottom-five graded inside linebackers in the NFL. It’s impressive that they’ve still maintained a competent scoring defense, but its one that’s liable to crack any week.

The defense is the Steelers’ biggest question mark, but the gauntlet they have to run may ultimately be their downfall. If the playoff seeding holds up as it is right now, they’d have to travel to Denver, then New England and then face whoever emerges from Cincinnati’s side of the bracket. While Pittsburgh just beat the Broncos at home, playing at altitude is a different environment and I’m sure defensive coordinator Wade Phillips will rethink his blitz and man coverage-heavy game plan next time around. The real matchup problem for the Steelers is undoubtedly the current No. 1 seed, New England. The Patriots’ offense plays at a level that can match Pittsburgh when fully healthy and they have far fewer question marks on the opposite side of the ball. Rob Gronkowski poses serious complications for that Pittsburgh linebacking corps

The Steelers are playing the most exciting brand of football in the NFL. Exciting doesn’t win championships though. Balance and consistency is required to run a multi-game stretch and bring home the Lombardi Trophy. Until their defense can exhibit that, the Steelers will be just another elite offense lost to history.

Mike Renner is a writer for Pro Football Focus and a contributor to The Washington Post’s NFL coverage.

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