But at some point in August, they expect to be back where they belong, working side-by-side at inside linebacker in Defensive Coordinator Wade Phillips' 3-4 alignment.
Added Trevathan: "I'm moving. I'm shuffling. I'm doing our drills. I'm doing everything right now; I'm just limited on contact. …
"I'm feeling good right now, I'm not going to lie. But I want to feel great before I go out there again. I think I owe this team and I owe this city."
Both will have something extra when they come back. Marshall will have two screws in his foot; they were placed there during offseason surgery to aid in his recovery from the mid-foot sprain he suffered last Dec. 14 at San Diego. The screws will be removed after the season.
"I haven't really done a whole lot on [the foot]," Marshall said. "I do a lot more in the training room. My surgeon told me it will probably bother me a little bit throughout the whole year -- nothing to keep me out."
Trevathan is playing with a reconstructed kneecap, repaired in surgery after he dislocated it Dec. 14. That was the last of the three injuries he suffered around his knee during the 2014 season.
"It's been a little rough, but I'm taking this time to really get my body right, really get my mind right, and I think it will be beneficial," Marshall said.
Some preseason game work would also help both linebackers as they transition to new roles in the 3-4 after leading the Broncos in tackles from the weakside position in the 4-3 alignment the last two years.
"I might need to play maybe a couple of series in a game or something like that," Marshall said. "But I think that mentally I've always been locked in and dialed in. I think I'll be able to handle it if I don't get as many reps as they would want me to get.
"If this was last year's defense, I think no one would really ask if we needed to play, because it's the old system," Marshall added later. "But I think a new system, you would want to get in and get acclimated to it."
That's true even though the system is "not as intricate" as last year's defense.
"We don't [have] to make too many checks. Basically we've just got to play with the look and we just do what we do," Trevathan said.