Change has been the only constant with the Broncos defense over the last several years.

For the sixth time in as many years the Denver Broncos will open the season with a new defensive coordinator who is will be implementing a new defensive scheme with a handful of new defensive players.  
The new defense figures to stay around for at least a little while longer than have the previous six. The powers that be at Dove Valley recognize the Broncos will not be turned around overnight. The organization’s leadership structure believes in new head coach John Fox, his defensive coordinator Dennis Allen and the brand of football they are bringing to Denver.
Allen and Fox share a similar philosophy on how assemble and coordinate a defense.  They figure to work well together. Allen said Fox has given him full leeway to coach the defense as he sees fit but adds that he and Fox have to “do a good job of blending (their ideas) together."
"We're going to be attacking and aggressive and as physical as we can," Allen said.
This is one of the oldest and oft-used clichés in the NFL lexicon; have you ever heard a defensive coach say they want “a lax, conservative defense that going to use a lot of soft zone and shy away from rushing the quarterback”? Of course not.
Yet looking at Fox’s and Allen’s history, as well as watching the team practice and play, one gets the impression they mean what they say. 
Further elaborating on the aggressive, attacking approach he will employ, Allen said, “"it's partly scheme but a lot of it is just mentality....we want to be a violent, aggressive defense….we're gonna hit you as hard as we can."
Allen and Fox want the defense to force negative plays – sacks, tackles for loss and turnovers. Allen notes that the 2009 Super Bowl Champion New Orleans Saints, for whom he served as defensive backs coach, forced 39 takeaways.
Allen has been well-received by his players. 2009 NFL sack king Elvis Dumervil says, “I love his mentality, he gets you fired up just talking to him, I got pumped up just listening to him."
Asked how to go about forcing negative plays Allen says, "I think first and foremost you have to put guys in position to be successful.”
Two of the guys who Allen and his staff will be putting in positions to be successful are rookies – linebacker Von Miller and safety Rahim Moore. Both players’ collegiate careers and skill sets indicate they will be highly capable of creating those negative plays.
In his senior season at Texas A&M, Miller tallied 17.5 tackles for loss and 10.5 sacks. And Moore tallied 14 interceptions in his three years at UCLA, leading the nation in picks as a sophomore.
In Denver’s base defense, Miller will line up off the ball at strong-side outside linebacker. From there, the defense can disguise what Miller is going to do; the opposing offense will not know if Miller is going to be blitzing or dropping into coverage.   
On passing downs, the Broncos will use their nickel package which has Miller lining up in a three-point stance at left defensive end with Robert Ayers sliding inside to three technique “under tackle” position.
In Dumervil, Denver has another negative-play creator on defense. It is hard for Allen to contain his excitement about having both Dumervil and Miller – who’ve dubbed themselves Batman and Robin – going after the quarterback.
"I get kind of excited about it,” Allen said with a big smile, “their best quality is their ability to rush the passer."
Dumervil, fully recovered from the torn pectoral muscle that cost him the entire 2010 season and now 15 lbs heavier and noticeably stronger, is equally excited about the new defense and playing with Miller saying, "I've never had a sack guy opposite of me ... I think Von is a natural pass rusher ... look for him to do great things in the NFL.”
A stout pass rush will make the defensive backs’ jobs easier. Allen calls the Denver secondary – with Moore, veteran Andre Goodman and future Hall of Famers Champ Bailey and Brian Dawkins – the strength of the defense.
Speaking about the defensive changes the veteran Dawkins says, "We're building, we started off at the right place, everybody running to the ball everybody getting to the ball with an attitude." Dawkins recognizes the “aggressiveness” cliché and says, “It's one thing to say it, it's another thing to do it on a consistent basis.”
Only time will tell if Denver can consistently be disruptive defensively, but they appear to have an excellent mentality and a lot of the right pieces in place.