When the news broke that Danny Trevathan would go out with an injury, so did the hearts of many Denver Broncos fans. Last summer, Terrance ‘Pot Roast’ Knighton was asked who the most important defensive player was. Without hesitation, he named Danny Trevathan.

The only good news was that Denver was flush with talented young linebackers. They have Von Miller back from injury and starting to develop his old skills, while Nate Irving is opening some eyes. Denver’s young linebackers looked good in camp and preseason.

Denver had again picked up a quality player. This time, the lowly Jaguars didn’t see a future for him. Richard Smith and Jack Del Rio disagreed. As I’ve said before, I don’t argue with those two regarding linebacking.

Enter Brandon Marshall, linebacker.

Denver’s first Brandon Marshall is now playing catch with Jay Cutler in Chicago. Marshall the linebacker was waived three times by Jacksonville before landing on Denver’s doorstep. He spent most of the 2013 season on the practice squad, until Von Miller's ACL tear created a roster vacancy.

Marshall might have continued to languish on the PS, if it weren’t for the Broncos' offensive players. Brandon kept flying around during practice, and the players were getting in John Fox’s ear. Fox went on to say,

Our offensive players loved him. He was running around on the practice squad last year, and I finally said to the guys, 'Hey, we can't block this dude.' He's on scout team wrecking our offense.

Marshall had no trouble making the 53-man roster this year. Moreover, he was tagged to step into Trevathan's shoes when Danny went down with a fracture of the upper tibia. It was a classic case of ‘next man up’. You don’t know what you’re getting when an unknown young player steps in for one of your top linebackers.

In his first two professional starts, Brandon has been eye catching. He leads the team in tackles with 18, two more than Nate Irving has. That ties him for sixth in the AFC, and 10th in the NFL. He’s played all 162 regular season snaps to date, so he’s in the base package at Will. He plays linebacker in the nickel and the dime packages. He even added a special teams tackle against the Colts.

Brandon was targeted 10 times in Week 1 by Andrew Luck, and gave up eight receptions. KC watches film too, so Alex Smith targeted Marshall six more times in Week 2. He allowed only three receptions, the longest of which was for seven yards. Brandon added a sack on Smith, a QB hurry, and a forced fumble. It was the best game of his short career.

Marshall isn’t Danny, but there are similarities. Looking at Trevathan’s first season (2012), he played each game from the fourth week through the playoffs. It took him until Week 9 to score a sack, and he didn’t have a QB hurry until Week 12. In limited snaps, he didn’t reach the number of Marshall’s 18 tackles until Week 13.

But Trevathan came back in 2013 and tore the league up. Knighton called Trevathan the best player on the Broncos defense last year, in what was just Danny's second season. Marshall’s production is above where Trevathan’s was at the same point in his career. That could speak well for how he’ll fare. Hopefully, he’ll do it for the Broncos.

There’s a point there worth considering. Denver has lost their defensive leader, the guy with the green dot on his helmet. He led the team in tackles in 2013 plus three interceptions and three forced fumbles. He was fifth in the AFC in tackles with 129. He had two sacks and was tied for fifth in the NFL with 13 passes defended. He came a long way fast. It’s hard to replace that kind of production and harder to replace that kind of leadership.

The Broncos are coming off two performances in which the defense struggled in the second half. Part of the reason for that is that they’ve lost their leader. If you recall what happened in the wake of Al Wilson’s injury, you can recognize the effect such a circumstance can have on a team. Marshall has leg-tackled, letting the runner fall forward. He’s vulnerable in degree to the pass. Despite these issues, he’s playing every down. He’s not Danny, but he’s a very good player.

Danny won’t return until after the bye week. What the Broncos will do with Marshall when Trevathan returns is a good question. You want to get your best players on the field. Nate Irving is second on the team in tackles, despite having been injured for much of the season opener.

With your key defensive player returning, where do you put the guy who’s been leading in tackles? Marshall needs improve his coverage skill if he's to maintain his role as the second LB in nickel and dime packages.

What Denver won’t do is to take away snaps from Trevathan. DeMarcus Ware, T.J. Ward, and Aqib Talib are more experienced, and were brought in to increase the defense’s physicality and effectiveness, but they’re new to the team. So far, the squad been more physical at times, but it seems to want to coast in the second half. I think that Danny will be a big part of ending that. His intensity and leadership qualities are irreplaceable, but he’s still weeks away from returning.

Until then, Marshall needs to maintain the level of play that’s put him at the top of the Broncos’ tackling stats. A second-year player who’s making his first starts isn’t going to lead Denver. That doesn't mean that his work can't provide a level of stability for the defense. Leading by example and leading the team in tackles are good ways for him to contribute. So far, Brandon’s done well.

John Elway often talks about not drafting All-Pros, but developing them. If Marshall can find a niche and continue to play at and above this level, he could fulfill that equation when Danny returns. Von Miller’s obviously still recovering, and Nate Irving has played well in about half the snaps. If Marshall can play as well at Will and in the nickel and dime package, this team can go far.

Depth remains essential. You’re only as good as the worst player on the 53-man roster. Despite having lost some focus in the second halves, the Broncos have been scoring enough to win games. If the promised defense shows up, that's going to get easier. If they don't, it's going to be a tough year.

The team needs to show more skill, focus, and tenacity in the second halves, but I won’t complain too much about a 2-0 start. As the Kansas City game showed, divisional games are often strange. The teams know each other well, and unusual outcomes are frequent. Denver played a solid game against the Colts, despite a dropoff in the second half. In both games, the defense showed considerable fire by shutting down first-and-goal situations. Now it’s time to put two good halves together.

The Seahawks are coming off a loss on the road to the Chargers, and Denver will have to face them in the most difficult of environs. Seattle tends to put together all four quarters - especially at home, where they've only lost once going back two seasons. Their defense of last year led the league in takeaways, points allowed, and yards allowed. The last time a team led in all three categories was the 1985 Bears. 28 years is a long time for a record to stand.

This is a major test of how far the Broncos have or haven’t come. The Super Bowl isn’t applicable, since it was a neutral site, not to mention last season. Seattle doesn’t lose at home. Denver will have to play its best if they want to leave the state of Washington with their record unblemished.

Brandon Marshall, among others, is going to be tested in ways that he hasn’t seen before. How he reacts to that challenge could be a big part of how well the Broncos play. He was once a chubby kid who was asked to block for a skinny kid named Quinton Carter. Now they’re together out on NFL fields in nickel and dime sub packages.

They will have to be at their best to slow Russell Wilson and his cohorts. Peyton Manning and his offense will have to put up plenty of points to give the defense a chance. It’s a major test for Denver, just three weeks into the season.

I can’t wait to watch it.