The Pittsburgh Steelers endured a series of destabilizing events over the past three seasons, each capable of sending most franchises careening off course.

Cornerstone linebacker Ryan Shazier’s career-ending spinal injury in 2017, which threatened his ability to walk, could have derailed them spiritually and strategically. The tumultuous exits of Le’Veon Bell and Antonio Brown two years ago cost the Steelers two of the NFL’s best playmakers and injected unfamiliar drama. Ben Roethlisberger’s elbow surgery last year, when he was 37, could have convinced them to start over at quarterback.

When the Steelers reach a crossroads, though, they somehow keep marching straight ahead. The organization is defined by stability, having employed three head coaches, all of them Super Bowl champions, in the past 52 seasons. As staffs have changed, their core tenets have remained consistent in a manner unique across professional sports. They blitz. They find remarkable wide receivers. They win.

The Steelers have emerged this season not as a franchise trying to rediscover itself but as a burgeoning and modern juggernaut. Entering Sunday’s showdown with their blood rivals, the Baltimore Ravens, they are the NFL’s last unbeaten at 6-0, firmly established as one of its most balanced teams and a Super Bowl contender.

Roethlisberger has reclaimed a spot near the top of the league’s quarterback hierarchy while throwing to a multifaceted phalanx of young, electrifying wide receivers. Pittsburgh’s top-ranked defense provides a template for how to confront today’s offenses. Presuming the Steelers win two of their final 10 games, Coach Mike Tomlin will make it 14 straight seasons without a losing record in Pittsburgh, even after he was forced to play overmatched backups at quarterback last year while going 8-8.

Aided by his front office’s consistently fruitful drafts, Tomlin has shepherded the Steelers through recent travails. From Tomlin’s perspective, the permanence of the Steelers owes less to long-term vision than to total attention on the moment at hand. Solve enough of the small problems in front of your face, and over time the big problems looming over your head dissolve.

“We just try to win every ballgame,” Tomlin said this week during a media teleconference. “We don’t overcomplicate things. We’re singularly, professionally focused, particularly in-season. Our attentions are on this week’s challenge and the Baltimore Ravens and what they present us. Sometimes you can miss the forest for the trees. I think that simplistic approach aids us in terms of getting in and out of touchy situations and things that happen in this business, particularly at this level.”

The varying tantrums of Bell and Brown appeared to deal the Steelers consecutive episodes of uncommon turbulence. Dissatisfied with the lack of what he considered a sufficient long-term contract offer and concerned about overuse, Bell sat out the entire 2018 season. Brown chafed at the Steelers giving their team MVP award to fellow wideout JuJu Smith-Schuster, stormed out of practice and missed a critical late-season game. Pittsburgh traded him that offseason for mid-round draft picks.

At the time, the losses of Bell and Brown seemed to suggest Tomlin was losing his grip on the locker room. In retrospect, they seem like a signal of his strength. Tomlin coaxed tremendous production from both players, and once they left Pittsburgh, the difficulty of managing them was fully revealed. The Steelers have plugged in James Conner, a 2018 third-round pick, at running back and drafted multiple wide receivers — including Diontae Johnson and breakout rookie Chase Claypool — without suffering a falloff at either position.

“It’s one thing to just say it’s next man up, but you got to have a lot of guys buy in,” defensive tackle Cameron Heyward said. “We’ve dealt with our share of injuries. We’ve dealt with our share of external factors. I think everybody is like-minded: We don’t care how it gets done; we just got to get it done.”

This season has shown Tomlin’s ability to adapt on both sides of the ball. The Steelers boast a defense graded first by Pro Football Focus and ranked first in yards allowed. They have stars at every level who thrive at causing turnovers: pass rusher T.J. Watt, safety Minkah Fitzpatrick and, before a season-ending injury, linebacker Devin Bush, for whom the Steelers traded up to draft last year and fill the long-term role once envisioned for Shazier.

With the notable exception of Fitzpatrick, a trade acquisition last season, the Steelers have built their defense the same way they have for years: through the draft. Defensive coordinator Keith Butler said the Steelers prefer to “raise” their own players so that they understand the team’s expectations and responsibilities. When the Steelers consider adding a defensive player, they first ask, “Are they physical, and can they run?”

General Manager Kevin Colbert “has done a great job since he’s been here,” Butler said. “We go in there, and we talk about the type of people we want on our team. Character is a major part of it. They’ve done a great job of getting guys who are very competitive.”

The star power helps provide a sneaky advantage. Underlying statistics suggest the Steelers have excelled at stifling short passing, one of the most important offensive components in today’s NFL.

The Steelers challenge quarterbacks to hold the ball and throw accurately downfield. Though the approach exposes them to long gains, it also yields drive-killing sacks and game-altering turnovers, the best weapons against offenses that operate under modern rules.

The Steelers prevent completions better than any other defense in the NFL. Quarterbacks complete 58.4 percent of passes against them, and they manage just 19.7 completions per game. What’s telling is the kind of throw quarterbacks are completing against Pittsburgh: The average throw of a quarterback playing the Steelers sails 10 yards past the line of scrimmage, second longest in the NFL. The Steelers have given up 12.5 yards per completed pass, which is second most in the league.

The Steelers blitz with more frequency than any team in the NFL other than the Ravens. They sack quarterbacks on 11.4 percent of dropbacks, most in the league. They take away the ball on 16.1 percent of the opponent’s possessions, which ranks sixth.

“We just want to be competitive in all circumstances,” Tomlin said. “We don’t want to have any holes in our game, so we try to be competitive regardless of what style of play someone tries to play. It’s probably just born out of that, of having a well-rounded menu and having well-rounded players that are competent under a variety of circumstances.”

While taking away the underneath passing of opponents, the Steelers have largely built their own offense around short, quick passes, including run-pass options. Roethlisberger holds the ball 2.29 seconds before release, the lowest average in the NFL. Pittsburgh offensive coordinator Randy Fichtner said the Steelers treat early-down passes like running plays, trying for short gains that soften the defense and set up easy conversions.

Ravens defensive coordinator Don Martindale compared Roethlisberger to a baseball pitcher who undergoes Tommy John elbow ligament reconstruction surgery and returns throwing harder and with more precision.

“It surprises me that he is left out, I think, of the conversation when people are talking about the ageless wonders like Drew Brees and Tom Brady,” Martindale said. “He’s playing at a high level right now. He’s playing at a really high level.”

Martindale said the Steelers’ passing game remains in the mold of Roethlisberger and Tomlin, but he sees a “splash” of a new influence. This offseason, Tomlin hired longtime college assistant — and onetime Maryland interim head coach — Matt Canada as his quarterbacks coach. He had taken note of Canada as he called plays in the mid-2010s (including as the University of Pittsburgh’s offensive coordinator in 2016), when Canada spawned the fly sweep and was an early innovator with jet motions that have spread throughout the NFL.

“I just thought he’d add a different eye to our process,” Tomlin said. “We take a collective approach to game-plan formation and little trinkets and things of that nature. He just brings a different perspective. Oftentimes when given an opportunity to add an assistant, I’ll add someone from the college ranks because of that fresh perspective on the game that they bring.”

The Steelers are willing to evolve but unwilling to budge from the foundation of their success. When Fitzpatrick arrived last year, he said, the “constant competitiveness” that emanated from Tomlin struck him. Tomlin has grown to be an institution in Pittsburgh such that his frequent utterances — reminders that “the standard is the standard” and references to “nameless, gray faces on the other sideline” — are civic catchphrases.

The road has not been smooth, but the Steelers again have arrived at a marquee game against the Ravens, the 5-1 reigning AFC North champions. Roethlisberger was sidelined for last season’s meetings, and he missed the intensity of the rivalry. In another franchise, he may not have received another chance. The Steelers are different.

“We always just stick together,” Roethlisberger said. “We always talk about, no matter how a game unfolds, we always do it together.”