There are plenty of reasons the Denver Broncos defense is excelling. Wade Phillips 3-4 scheme, paired with the talented pass rushers and great cover corners get the most press, but one of only two new Broncos to start on defense has quietly been a key for the NFL’s top-ranked defense.

Darian Stewart joined an already stacked defense during free agency last spring with little need personnel-wise. The addition of Phillips to the coaching staff meant a scheme transition but a mentality was missing from the “quarterback of the defense.”

“Oh man [Darian Stewart] fits great,” Veteran cornerback Aqib Talib said emphatically Thursday. “Having two safeties who will come down and pop you like that puts a lot of fear in wide receivers’ hearts. We kind of lacked that last year from the free safety and Stew definitely brought that to the table and you can see how much that has helped us.”

In more blunt and certain terms, long-time Broncos safety David Bruton Jr. commented on what Stewart brings that was lacking last season saying, “A free safety that would tackle.”

Rahim Moore was the safety the Broncos relied on for years to patrol the deep middle, prevent big plays and come up and make big tackles, but more often than not, his lack of physicality cost the Broncos. Moore left via free agency and Stewart came over after one season with the Baltimore Ravens and five seasons in the NFL (69 games and 33 starts) with head coach Gary Kubiak. Since his arrival, he has started all but two of the team’s first 11 games, participating in 89% of the defense’s plays (3rd most on the defense).

“He’s been a great addition to our team. Of course, I was on the other side of the ball last year, but just going against him every day, I had a lot of respect for him and a lot of respect for how smart a player he was,” Kubiak said Wednesday. “Obviously, it’s a heck of a secondary. I think he has fit right in with those guys in his work habits and his expectations as a player each and every day. [I am] very proud to have him.”

It took just one regular season game on the team to show how important an addition he was. In Week 1, Stewart came up with the game-saving interception in the end zone against his former team, the Ravens, with just 36 seconds remaining while holding onto a six-point lead.

He has carried the same big-play ability through 11 games, compiling 47 total tackles, one interception, one forced fumble, one fumble recovery and six passes defended. Despite showing great versatility, almost every one of his teammates mentions his physical play first when asked about their free safety, possibly due to the absence of that trait in recent seasons.

“He is more physical than Rahim [Moore] was. He’ll come down and hit. You saw that Sunday,” Bradley Roby said Wednesday.

Stewart had two big hits in Sunday’s win versus the New England Patriots. A fourth quarter pass break up by Stewart on Rob Gronkowski sidelined the All-Pro tight end and had many fearing for his playing future. Both Stewart and Patriots quarterback Tom Brady deemed the hit legal and it was just a reminder of what he brings from the back of the defense. When asked if Stewart “fits” on the team, newly converted safety Omar Bolden quickly answered.

“Hell yeah, no question [he does]. We take pride in being physical and being great in coverage too. He definitely fits the mold. He is one of us. He is very physical back there and he is reliable as well. He has done a great job for us and I’m happy to be playing with him.”

Phillips also echoed Kubiak’s comments on Stewart’s play, but believes it is what he brings from a mental approach that has helped the unit as a whole this season.

With the absence of many new pieces to the defense it may have been an awkward and time-consuming transition for Stewart. But according to teammates and himself, he has melded with the group and made instant contributions to a defense that excelled in its own right last season.

“The transition has been smooth. Football is football and we have a bunch of smart guys in the room so we talk enough to help each other out. I feel like I fit right in. I have a bunch of great players around me that can make their own plays. That is all you can ask for.”

Stewart has been a part of a defense that allows just 285.8 yards per game (tops in the NFL) and 197.1 per game through the air. As a unit, they have yet to allow a 300-yard passer while playing the likes of Joe Flacco, Matt Stafford, Aaron Rodgers, Andrew Luck and Brady. Stewart loves playing with Chris Harris Jr. and Talib for the simple fact that they eliminate targets for quarterbacks even before most snaps.

“When we have two great corners like that it makes it a lot easier for the safety because you can process their match ups right away. Once the two of them lock up their receivers, the quarterback is forced to go somewhere else.”

Stewart has yet to gain national recognition and is not currently listed in the top five of the NFL’s free safety Pro Bowl vote getters, but he is a big reason the Broncos are winning games and striking fear into opponents. In his postgame interview Sept. 13, following his huge interception versus the Ravens, he spoke about how good this defense could be.

“I think that we can be No. 1 absolutely, without a doubt. From the rush to the secondary and linebackers, I think that we have what it takes. It’s just staying consistent and just playing ball. I was thinking the other day, the potential that we have in that room is big. Every week there’s someone that’s going to have to see us.”

From top to bottom, Stewart has been the definition of consistent and despite his quiet demeanor and the little attention he is getting, his play is speaking volumes. He is certainly a giant reason the Broncos defense has become as good as he expected.

Email Sam at sam@milehighsports.com and follow him on Twitter @SamCowhick.