Since the 1970 AFL-NFL merger, the only time the Broncos have finished last in the NFL in both scoring and total defense was in 2010. That wayward unit allowed 29.4 points and 390.8 yards per game.

The Broncos now are worse than that. Way worse.

Denver ranks No. 32 and last in the NFL in scoring defense, giving up 37.5 points per game, and in total defense, allowing 461.5 yards an outing.

After the Broncos (1-3) won their first game of the season Sunday, overcoming a 28-7 deficit late in the third quarter for a 31-28 triumph at Chicago, there was a good share of celebrating. But there also now is a realization there remains plenty of work to do to fix the defense.

“I said this to the team (Monday), I said, ‘ I’m encouraged that we fought back into that game, but, man, let’s not finish (Monday) when we’re done watching this tape and feel like we’re content at all with how we played,’’’ Broncos coach Sean Payton said when asked about his defense. “(There are) too many things that still are disappointing or things that we have to clean up.”

For much of Sunday’s game, the Broncos were pushed all over the field by a Chicago unit that came in ranked No. 29 in the NFL in total offense. For the game, the Bears rolled up 471 yards, including a career-high 335 through the air by quarterback Justin Fields and 171 by the team on the ground.

The Broncos, though, were able to come up with three huge defensive plays late in the game to complete the comeback. Nik Bonitto, who had 2.5 sacks, had a strip sack of Fields and fellow outside linebacker Jonathon Cooper scooped up the fumble to run 35 yards for a touchdown to tie the score 28-28 with 6:55 remaining.

Denver stopped the Bears on a fourthand-1 run at the Broncos 18 with 2:52 left. Then, after Denver and taken a 31-28 lead, safety Kareem Jackson clinched the game with an interception.

So can a strong finish spur on the defense entering Sunday’s game against the New York Jets at Empower Field at Mile High?

“Yeah,’’ said defensive end Zach Allen. “We have the talent and we have the players. It’s just a matter of us just executing better. We saw flashes of it in second half. When we do it right, we play at an elite level. And we just have to continue working at it.’’

Defensive coordinator Vance Joseph has been getting plenty of heat, especially after a 70-20 loss at Miami on Sept. 24, when the Broncos became just the third team in NFL history to give up 70 or points in a regular-season game. But Allen, who played for Joseph when Joseph was Arizona’s defensive coordinator the previous four seasons, voiced his support for him.

“He’s been very successful in this league for a very long time and he has accomplished a lot,’’ Allen said of Joseph, who has been an NFL coach since 2005, including 2017-18 as Denver’s head man. “Everybody wants to point the finger at somebody but at the end of the day, you watch the Dolphins game, you watch the first half, it was either guys not tackling or guys not doing the right assignment. It wasn’t a question of the scheme or anything like that.

“I think a lot of people probably don’t understand the big picture. For us, it doesn’t really matter. We know what we’re doing, what we’re working on it. Everybody can say whatever the (heck) they want to say. But at the end of the day, they’re not in the arena. I love (Joseph). I think we’re going to be fine. We’re going to do great things. It’s still early but we’re going to turn it around.”

Injuries have played a role in Denver’s defensive struggles. Safety Caden Sterns was lost for the season in Week 1 due to a knee injury. The Broncos have been without pass rusher Frank Clark (adductor) for the past three games and star safety Justin Simmons (hip) for the past two. Linebacker Josey Jewell (groin) and defensive tackle Mike Purcell (ribs) both were hurt at Miami and missed the game at Chicago.

In a 35-33 home loss to Washington on Sept. 17, Jackson was ejected late in the first half after a penalized hit on a touchdown catch by tight end Logan Thomas. That began a stretch in which Denver’s defense gave up more than a point a minute.

The Commanders charged back in that game from a 21-3 deficit to score 32 points in the final 32 minutes. Then came the 70-point debacle at Miami and allowing 21 points to the Bears in the first 24 minutes. Put it all together and that’s 123 points in 116 minutes.

Jackson was encouraged by Denver finally turning things around at Chicago. And he believes the Broncos, who were seventh in the NFL in total defense last season, can get back to that level.

“I know the guys we have on our side of the ball,’’ Jackson said. “We’ve got a ton of competitors. We’ve got the same group of guys we had last year, a unit that was one of the best in the game. So for us, if we communicate and we do things the right way, we’ll be pretty tough to beat. And we’ve got to do it all of the time, not some of the time.”

The Broncos could have Simmons and Clark back to face the Jets, and that would help. After that, though, they play defending Super Bowl champion Kansas City in two of three games and then it’s off to play at high-scoring Buffalo.

So it’s understandable the Broncos were pleased to step up late on defense at Chicago and finally get a win. But they know there is plenty of work to be done on that side of the ball.

“The win feels good,’’ said defensive end Jonathan Harris. “But we’ve got to learn from the film and move on.”