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An Analytics-Based Breakdown of Broncos' Roster Needs Post-Free Agency | Defense

How much headway did the Broncos make in bolstering the defense via free agency? Here's a look at the roster through the lens of analytics.
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With the first wave of NFL free agency in the books, GM John Elway and Denver Broncos have decided to hit the 'pause' button while evaluating their next move. The Broncos are likely taking another hard look at their roster for weaknesses before diving back into the free-agent fray. 

The other option would be to stand pat and wait for the draft to address those areas. No NFL team has a roster without voids or weaknesses. 

The salary cap doesn’t allow for 53 stars on the team. The key is knowing those weaknesses and understanding whether they're balanced adequately by the strengths on the team.

How many weaknesses do the Broncos have on the roster? What are their areas of strength? 

Analytics will uncover both rather quickly. We dive into the analytics using Pro Football Reference's Performance Value (a metric that I have used many times in past articles) to identify strengths and weaknesses of each defensive position group currently on the Broncos' roster.


Analytics identified the linebacking group as an area of strength for the Broncos. Currently, three of the four projected starters, Von Miller, Todd Davis, and Bradley Chubb, have an average career Performance Value above the mean (average) for the position. 

Miller is significantly higher than the mean, which is exceptional. He is in the 'elite' category in Performance Value.

If not for the injury last year, Chubb would be approaching the 'elite' group. If he stays healthy, that is the expectation based on past performance.

Alexander Johnson would be significantly above the mean if his first season was excluded. It isn’t excluded in this analysis, but there is a valid reason to do so since he was coming back from a lengthy absence from football due to legal reasons.

The key reserves, Malik Reed and Josey Jewell, are also above the mean. If the Broncos were to keep 10 linebackers on their roster, as they did last season, 60% of the corps is at least above the mean (excluding Johnson’s first season). That is a solid group.

The concern for this group is that two of the starters, Miller and Davis, are at the age when linebackers start to decline. Miller is an anomaly, and I fully expect that he will play at a higher level into his 30s, similarly to how other potential Hall of Fame players did in the past.

Davis is a bigger concern. His Performance Value has not consistently been exceptional through each year of his career and his decline is more likely to happen rapidly in the next two seasons. The Broncos should explore upgrading this position group in the draft, but it is not the biggest area of concern.

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Defensive Backs

Analytics identified the defensive backs position group as an area of concern, but not a complete weakness. The Broncos have three players who have a career average Performance Value above the mean for the position; Justin Simmons, Kareem Jackson, and A.J. Bouye. 

Simmons is an ascending player and will likely be considered in the elite Performance Value group soon. Jackson is entering the twilight of his career and even though he had a good season last year, a drop off in Performance Value is expected. 

Bouye is in a similar boat. His peak Performance Value season was at age 26 and he will be 29 years old this season.

The rest of the players at this position group have an average career Performance Value below the mean. If the Broncos are to keep nine players as they did last season, only 33% of them are above average. That is concerning. 

This could be helped with Bryce Callahan being healthy and having a good season, but that is not certain. The Broncos would be wise to sign a player in the second wave of free agency and also look to the draft for a player or two to bolster this group.

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Defensive Line

Analytics identified the defensive line as an area of weakness. Only one player, Jurrell Casey, has an average career Performance Value above the mean for the position. 

In fact, it is significantly higher and he has consistently had seasons of high Performance Value. His age is a bit of a concern, but it is tough to deny his production over his career.

After him, things turn rather bleak. Dre’Mont Jones is coming off a promising rookie season and Mike Purcell had a solid first season with the club, but both players still have much to prove. Jones could be the future along the defensive line if he builds on his rookie season. As we have seen in the past, that is no guarantee.

Unfortunately, Purcell could have just had a 'flash in the pan' type season. People tend to forget that he has played four seasons in the NFL and spent some time bouncing around practice squads. 

Purcell is also turning 29 years old before this season begins. In three of the four seasons he has seen game snaps, his Performance Value has been well below the mean. He could be one of those players that has a solid two or three seasons later in their career and we have seen in past analyses that defensive line players tend to ascend in performance until 30 years of age. It is still a significant risk to count on that from Purcell, though. 

The rest of the players in the position group are below average. Most won’t be on a roster in September. If the Broncos keep six players, only one (17%) will have a Performance Value above the mean when the games begin. That is a huge weakness on this roster.

It is imperative that the Broncos upgrade this position group. Unfortunately, Denver missed out on some key young free agents that were identified in past analytics. The team should look at both the second wave of free agency (slim pickings left) and early in the draft to rectify the situation along the defensive line.

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What it Means

The Broncos have the makings of a solid defense, but must find solid help along their defensive line and in the secondary or hope that some of their players make a significant jump in performance for this defense to be great. 

The Broncos' biggest area of need is the defensive line. The area of strength is with the linebackers. One ray of hope is the strength of the linebackers can help to alleviate the weakness that is in the defensive line, especially on passing downs. But you can't count on it. 

Follow Thomas on Twitter @ThomasHallNFL and @MileHighHuddle