ENGLEWOOD, Colo. -- With the NFL's scouting combine set to open Tuesday and free agency to follow March 9, today marks the seventh installment of a position-by-position look of where things stand for the Denver Broncos at each spot on the depth chart, the salary-cap commitment, free agents and where their needs are greatest.

Today: Defensive backs.

Tuesday: Special teams.

The roots of the ability of the Broncos' No. 1-ranked defense to cover a variety of options opposing offenses had to offer in their Super Bowl run reach all the way back to 2011, when John Elway took his current job as the team's executive vice president of football operations/general manager. Shortly after he made the transition from businessman/celebrity Hall of Fame quarterback to full-time NFL executive that year, he was asked if he believed in the long-held premise that quarterback, left tackle and edge rusher were the three "foundation" positions in team building.

Elway agreed they were and then quickly added; "And corner ... the way teams are throwing the ball -- and it's only going to increase, you're going to need to invest at corner to have the depth you're going to need."

The leader of the Broncos' secondary, Chris Harris Jr. has become one of the NFL's top cornerbacks after going undrafted in 2011. Ben Margot/AP Photo

Fast forward to the Broncos' Super Bowl 50 win. There's Chris Harris Jr., who was signed to a five-year, $42.5 million deal in December 2014, starting at one cornerback spot with Aqib Talib, who was signed to a six-year, $57 million deal in March 2014.

And as the No. 3 was Bradley Roby, who the Broncos used a first-round 2014 pick to acquire despite already having Harris and Talib. And as the No. 4 cornerback, Denver drafted its No. 4 in Kayvon Webster, who the Broncos selected in the third round in 2013. That is significant investment, in the draft and with the team's financial resources, at cornerback.

"Rush and coverage, it all goes together," Harris said. "But we feel like we had the guys to match up with anybody."

The Alpha: Talib and safety T.J. Ward have big personalities, along with their respective games, so each also has a big presence in the locker room. But in terms of tenure, performance and leadership, Harris not only has Champ Bailey's former locker, but he is also the hub of the wheel in the secondary.

Salary cap: The Broncos have certainly made the investment in the secondary. Talib will count $9.97 million against the cap in the 2016 season, Harris will count $9 million, Ward is at $5.75 million and Darian Stewart is at $3.25 million. Roby, at $1.896 million, is the other player currently under contract in the secondary who will count more than $1 million against the cap.

Pending free agents: Safety David Bruton Jr., who has been the team's special teams captain the past three seasons, also enjoyed his most playing time in the team's defense this past season. Bruton played 482 snaps (43.8 percent of the team's total) in Wade Phillips' defense during the regular season and Bruton, who is a Broncos' 2009 draft pick, is an unrestricted free agent. Omar Bolden, who had the team's longest punt return (83 yards for a touchdown) and kickoff return (41 yards) this season, is also an unrestricted free agent. Late arrivals Shiloh Keo (unrestricted) and Josh Bush (restricted) are also free agents.

Who could stay: The Broncos would certainly like to keep Bruton, a leader on and off the field, but they have a long list of free agents, so he certainly could get caught in the squeeze. For his part, Bolden's ability to stay could simply depend on what kind of interest he gets from the outside as he has the profile of an at-the-right-price player for the Broncos.

Who could go: Bruton, who will turn 29 just before training camp opens, has made no secret he's in search of the right combination of contract/playing time with this free-agency opportunity. With Stewart and Ward in place, he would be looking at the kind of situational work he had this past season. If he wants guarantees of more work with the starters, he may have to look elsewhere to get it and that would be a major loss. Bolden struggled to stay on the field this season with hamstring/knee injuries and that will impact any offers from the Broncos.

What they like/want: As long as Elway is calling the shots, they'll always be looking for cornerbacks in any offseason. With Phillips calling plays on defense, they also need players at all spots on the secondary who can survive at times in man coverage.

Need index (1 is low priority, 5 the highest): It's a 2, based on personnel already in place, but the Broncos will still look to use some draft capital to bolster the position -- they used two draft picks in 2015.