Here's why the loss of Mike Purcell is so damaging to the Broncos

When the Broncos placed defensive end Shelby Harris on the COVID-19 reserve list, it piled more misfortune on a position group that has faced more than not only any on the team’s roster, but perhaps more than any other position group in the NFL.

After three games, the Broncos lost defensive end Jurrell Casey to a torn biceps muscle. Three games later, nose tackle Mike Purcell succumbed to a lisfranc injury.

The Broncos were able to absorb the loss of Casey. But last Sunday, the absence of Purcell seemed to be too much to overcome. Without the core of their run defense, the Chargers shredded the Broncos on the ground for 210 yards, 5.53 yards per carry and 10 rushing first downs, all of which were the most surrendered by the Broncos this season.

Broncos coach Vic Fangio said this week that the rushing-defense woes were due to “fundamental errors.”

“It was disappointing there in that most of [the Chargers’ big runs] were just — all of them, really — were just fundamental errors on our part in calls that we play a lot,” Fangio said. “That we played a lot prior to the first half when we were playing the run good and when we played the run better late in the game. We had a stretch there where fundamentally we were off. Obviously, when you do that, you’re going to have problems, and we did have our problems.”

But the difference without Purcell was profound, and the data shows it.

Last year, the difference in per-carry average with Purcell on the field and without him was massive. Denver allowed 4.75 yards per carry when Purcell wasn’t on the field, but gave up just 3.63 yards with him.

This year, the difference is greater.

Meanwhile, the Broncos have allowed 864 yards on 190 rushing attempts taking place when Purcell was on the sideline or injured — an average of 5.78 yards. That is 2.30 yards more than the Broncos surrender when Purcell is on the field.

This impact illustrated why the Broncos signed him to a three-year contract last month. Purcell has been a perfect fit for Fangio’s defensive line. In occupying blockers, Purcell has opened up opportunities for Harris and starting inside linebackers Alexander Johnson and Josey Jewell.

“He does a lot of stuff,” Jewell said last month. “The biggest thing is when people are preparing for us, they see him and they know they’ll have to stay on the double[-team] longer. And when they stay on the double longer it means there’s a late release on us and they’re not going to get up to the second level as quick.”

No wonder Purcell is missed.

“It really hurt,” defensive coordinator Ed Donatell said last week of losing Purcell. “This guy has been a stout piece of our defense, but he’s missed time and we’ve had other guys miss time. So, we’re already used to rotating and that’ll be absorbed by two or three guys in different combinations.”

DeShawn Williams started and Sylvester Williams (no relation) rotated in, playing 31 and 24 snaps along the defensive line, respectively. But against a Chargers ground game missing first-team running back Austin Ekeler, Los Angeles gashed the Broncos for 210 yards and an average of 5.5 yards per carry. Los Angles’ three running backs — Justin Jackson, Troymaine Pope and Joshua Kelley — combined for 189 yards on 34 attempts.

Each of them had one run of at least 20 yards, meaning that the Broncos surrendered more explosive runs to running backs last Sunday than they did in the first six games of the regular season, when they only allowed two such gains to running backs. (Jets quarterback Sam Darnold and Patriots quarterback Cam Newton also had one explosive run apiece.)

Now take that defensive line from last week and potentially remove Harris because of COVID-19 protocols, and you face a daunting task against Atlanta’s Todd Gurley, who is second in the NFL in rushing touchdowns with 8.

“When you have guys like [Purcell] and [Harris], it’s amazing because they take those two blockers up,” Jewell said last month, “and you’re usually free or you get a late blocker that’s off balance and stuff like that.”

Freedom for the linebackers to make plays me be limited — and with that, the ability to stop the run could be in peril.