ENGLEWOOD, Colo. — We no longer exist in the age when the inability to run sinks an offense.

But for Rich Scangarello’s unit to operate at optimal efficiency, it must have the potential to sustain an attack on the ground, even if it does not necessarily have to rack up significant yardage totals.

The threat of the run matters. It can help the Broncos maintain a lead, chew the clock and remove pressure from rookie quarterback Drew Lock’s shoulders.

But the Broncos are in a funk on the ground. In each of their last four games and five of the last six overall, they have failed to rush for 100 yards as a team. In their last three games, their per-carry averages have been below 3.5 yards each time.

If they fail to reach 100 yards as a team against the Lions on Sunday, the Broncos will have their longest streak of games without triple digits on the ground since a nine-game stretch of the Josh McDaniels era from the end of the 2009 season through the first weeks of the 2010 campaign.

In some games, the inability to run did not hurt the Broncos much. Against Houston, for example, they were able to control the pace of the game through the air, taking what the Texans gave them.

“The Houston game, they forced us into a world where you need to throw the football,” Scangarello said. “They played close to the line of scrimmage and we were able to exploit that.”

A week later, early attempts to establish the run got lost in the snow.

“Last week with the weather conditions, we were trying to stay balanced,” Scangarello said. “Then, you come out at halftime and you score late and then they score and all of a sudden it’s 23-3. You don’t want to go away from your offense, but you know you have to have a sense of urgency, and at some point we got away from it. That’s where the throws came and really, you lose that balance.”

But what those games — and the others since Week 12 — have in common is the absence of fullback Andy Janovich.

In the seven games that Janovich played this season, the Broncos averaged 4.4 yards per carry and one first down every five attempts. In the seven games he missed to injuries, those averages dropped to 3.8 yards per carry and one first down every 5.5 attempts.

When breaking it down into per-snap production, the Broncos average 4.43 yards per carry with Janovich on the field and just 4.06 yards per snap without him.

Numbers like these show why the Broncos signed him to a new three-year contract on October 11.

“He’s been missed for sure,” Broncos coach Vic Fangio said. “I think [Andrew] Beck’s come in and done a good job, but Andy’s a good fullback and a guy that’d be good to have.”

Beck has shown some flashes with some key blocks, and his versatility makes him a quality depth piece that the Broncos should be able to utilize for years to come. With the ability to work at tight end, H-back, fullback and on special teams, he could carve out a role similar to the one established by Patrick Hape in a similar Broncos scheme from 2001-04.

But fullback is a position that usually takes years to master in the NFL, and Beck is learning the nuances of the position after working as a tight end in his football life until this season.

“They’re a lot different,” Beck said. “Both positions you have to be physical, but No. 1, you’re more at the point of attack as a tight end, just because everything is happening right in front of you. As a fullback, you’ve got to read coming from the backfield and it takes a little bit of adjusting, but hopefully I’ve done an all-right job, and I continue to grow every day with every practice.”

Fullbacks may be going extinct around the NFL, but for the Broncos, they remain essential. And while Beck learns and grows at the position, they’ve gotten another lesson in the value of Janovich to their running game.

First time without a 100-yard team rushing game since games 3-6 of 2016

9 games — Game 13 of 2009 through Game 5 of 2010

There remains a correlation between ground success and victory, although some of that is due to the desire to run more to protect a lead. Since 2016, when the Broncos rush for at least 100 yards, average 4.5 yards per carry and run at least 20 times, they’re 10-6, compared with 21-31 when they don’t meet all three of those standards.