When John Madden coached the Oakland Raiders’ semi-dynasty through the 1970s, he and owner Al Davis had a long and amiable disagreement about the best positions from which to build a team.

Madden loved the “big uglies,” his affectionate moniker for offensive linemen, the workhorse unit that coddles its QB and drives an offense downfield.

Davis thought a team’s greatness emanated from its speed, and he believed that you could construct a dynasty by starting with shutdown defensive backs.

In the end, they were both right: Among the Raiders’ many NFL Hall-of-Famers from that golden era are three O-linemen and two D-backs.

Although it might sting more than a little to lead off the 2016 Denver Broncos’ post-mortem with an analogy about the hated Raiders, in this case it’s apt. That’s because this season’s Broncos were dynamite in defending the pass, and godawful at doing all the things—running the ball, protecting the quarterback, controlling the clock—that’s expected of a good offensive line. (The Broncos’ defensive front seven also had a miserable time stopping the run this year, but that had as much to do with injuries and a lack of depth as anything else.)

Now that coach Gary Kubiak has resigned, due in part due to health reasons, Broncos’ president John Elway will begin looking for his third coach in his six years running the team. Although that’s normally a red flag of discontinuity for a professional sports franchise, the Broncos aren’t just any franchise.

The task of stalking the orange-and-blue’s sideline remains one of the plum jobs in any sport for several reasons: The recent disruptions owe more to individual personnel quirks—Peyton Manning’s extended swan song and the subsequent Brock Osweiler mini-drama, the health of Kubiak and longtime owner Pat Bowlen—than to any organizational instability. Meanwhile, the team’s nearly 50-year streak of home sellouts shows no signs of abating, and the remaining players still comprise one of the more talented rosters in the league.

By now it’s fairly conventional wisdom that the Broncos, with Chris Harris and Aqib Talib, have the best cornerback tandem in football (even Al Davis couldn’t deny that). Von Miller will likely finish among the top three in Defensive Player of the Year voting and is surrounded by a strong mix of young and veteran players. Even the offense that struggled so mightily this season has some excellent pieces in place—provided they keep developing the QB position.

That’s why Elway’s next hire will probably be an offensive-minded head coach, or at least one who can bring a QB-whisperer with him so the team can figure out, as quickly as possible, whether Trevor Siemian, Paxton Lynch, or TBD will be behind center in 2017. (Among the early candidates are Atlanta offensive guru Kyle Shanahan, Mike’s son; the Cowboys’ Scott Linehan; and the Raiders’ Bill Musgrave. All three have worked wonders with their respective signal-callers.)

But none of that will matter if the Broncos don’t significantly upgrade the O-line. To give some idea of how important this is, three of the five Dallas offensive linemen made the Pro Bowl this year. The unit is widely regarded as the class of the league and the unsung reason the team went from 4–12 in 2015 to 13–3 this year despite its two featured “skill” players being rookies.

The Broncos are nowhere near rebuilding mode; they could probably make almost no changes this offseason and still be a playoff contender in 2017. But if they really want to be dominant again they need to start thinking more like Madden and Davis.