ENGLEWOOD, Colo. --The Broncos arrived at UCHealth Training Center on Monday leading the league in total defense.

Imagine how good their defense may be if it can reduce the number of explosive pass plays it allows.

It's not that the Broncos are falling victim to an avalanche of deep passes; they're giving up one pass of 20 or more yards every 15.4 pass plays. That's the 10th-best ratio in the league. The 64-yard touchdown they allowed Sunday was the first pass of 40 or more yards allowed by the Broncos this season; only seven teams have done better.

But in Sunday's game, Oakland picked up 134 of its 254 yards on four pass plays of at least 20 yards. The gains came in clusters -- two each on Oakland's two scoring drives. Take those away, and the Broncos have a defensive performance for the ages.

"Yesterday they scored basically 10 points and we gave up a 64-yard pass," Head Coach Vance Joseph said. "We had them backed up both times and the second time we got them backed up minus five, I think. We gave a 28-yard pass up, which led to points. Defensively we're playing pretty good, but we could play better, especially in two-minute defense. We've been really soft there. We have to improve there."

Improvement starts with knowing what went wrong -- especially on the touchdown. Safety Darian Stewart said the score saw a breakdown that was similar to what transpired on the 38-yard score the Broncos gave up to Chargers wide receiver Travis Benjamin in Week 1.

"It just so happened to be the same play the Chargers ran on us. They caught us in the same type of play," Stewart said. "It was just a miscommunication for the most part. We've got to be better with technique, so we won't feel so threatened to drive stuff that was in front of us.

"But it's something that can be cleaned up. We just have to know when we get that look what's coming, and prepare for it."

And if the Broncos clean it up, its defensive ceiling could be immeasurable.

"That's the scary part," said safety Justin Simmons. "From the outside looking in, there's so much more that could be accomplished in this defense."

"That's the crazy part about it: We're just getting started," said nose tackle Domata Peko Sr. "I think we're just scratching the surface."

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STILL SEEING RED INSIDE THE 20**

After two weeks of struggles in the red zone, fixing the issues inside the 20-yard line will be a focal point of the Broncos' work between now and their return to action Oct. 15 against the New York Giants.

Denver got just 25 of a possible 56 points -- including a single touchdown -- in its last two games from eight drives that advanced to or across the opponent's 20, including just nine of 28 possible points Sunday. In Weeks 1 and 2, the Broncos scored touchdowns on seven of nine red-zone forays, racking up 52 of a possible 63 points from nine possessions.

In the games, the "why" of the Broncos' recent red-zone issues is clear. In Buffalo, one of the failed red-zone drives saw a penalty; another was bogged down by a pair of sacks for a combined loss of one yard. Sunday saw similar causes: a sack on one series, a penalty on another, and pressure that led to a 10-yard loss after a tipped pass that forced a second-and-goal from the Oakland 14 from which the offense could not recover.

But as Joseph reflected on the struggles, he saw the origins of these problems in practice.

"I thought this morning watching our practices from the last two weeks -- it's more of how we practice," he said. "Our Thursday practice is a practice of basically third downs, red zones, goal lines and short yardage. Our last period is red zone. I've watched it for the last two weeks and it's not very good. That's my fault.

"I'm going to move red zone up in practice so we can get more energy there. That part we're going to fix. We're going to spend more time in red zone. We're going to apply more detail and focus there as coaches and players. We'll fix that. But the concepts are there, and running the football is there. It's just more self-inflicted wounds."

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TIGHT ENDS STEPPING UP**

A.J. Derby's 22-yard first-quarter touchdown catch was the second by a Broncos tight end this season, matching the total for Broncos tight ends from the entire 2016 campaign.

Derby, Virgil Green and Jeff Heuerman are on pace for a collective 888 yards and eight touchdowns on 64 receptions. Last year, Broncos tight ends combined for 640 yards and two touchdowns on 53 catches.

Derby led the Broncos in receptions (four) and receiving yards (75) on Sunday. He was one of six players to receive game balls, joined by Simmons, Peko, wide receiver Bennie Fowler III, running back C.J. Anderson and defensive end Derek Wolfe.