ENGLEWOOD, Colo. -- Consider it the first day of school when all of the other kids got there five months before you did.

The Denver Broncos had five players in uniform Monday night who had been with the team for just days, and four of those players -- linebacker Corey Nelson, cornerback Duke Dawson, cornerback Davontae Harris and wide receiver/returner Diontae Spencer -- played in the game, a 24-16 loss to the Oakland Raiders.

"That's football, I guess," said Spencer, who spent four years in the Canadian Football League before the Pittsburgh Steelers waived him at roster cutdown. "You don't always know how it's going to go, so being ready for anything is part of it. But you are kind of trying to find your way around the building and figure out what hallway leads where."

"It's a bit overwhelming," Nelson said. "You look at it -- it was a pretty tall task on a big stage -- Monday Night Football -- having to learn a whole new defense within seven days. You feel good you're with a team, getting ready for a game, because that's absolutely what you want to be doing. But it can be a little overwhelming that first week. But I guess after 13 workouts last season, being on three different teams in the last year, I had a system (laughs). Maybe it prepared me."

Of the fresh faces, it was Nelson who played the most against the Raiders. The linebacker, a former seventh-round pick by the Broncos in the 2014 draft who spent the first four years of his career in Denver, played 46 snaps against the Raiders (84% of the defense's plays in the game) to go with three snaps on special teams.

Dawson, Harris and Spencer all played exclusively on special teams, while Allen was Joe Flacco's backup, but he did not play in the game.

After months of discussion about the Broncos' new schemes and how important the offseason work was for the players, last week was certainly far different for those who were simply tossed into the deep end of the football pool.

"It was a little extreme," is how Allen put it. "... I've been in an offense with similar terminology, so you kind of lean on that. But in your head you're kind of using things you know, that terminology, to learn the terminology, at least right away."

"I was thinking at least I knew my way around here," Nelson said. "You just keep moving, study and handle the idea you're going to have to learn fast."

Broncos coach Vic Fangio called it all part of "roster gymnastics," as injuries, roster decisions, trades and performance often lead to roster turnover. But the Week 1 arrivals usually find themselves awash in at least some disappointment at being released by teams they spent the offseason with to suddenly simply trying to find their lockers.

In Dawson's case, the Broncos traded a sixth-round draft pick to the New England Patriots the day before rosters leaguewide were trimmed from 90 to 53 players. Shortly after Dawson's arrival, he was asked what he believed his role could be in the Broncos' defense, and he simply said:

"I don't know. I just got here."

Those first days are a whirlwind of extra meetings and an almost constant run through the playbook.

Because it was a game week, the focus was not teaching everything the Broncos had shown to the players throughout the offseason, but rather just the information they needed for that week's game plan.

Nelson, for example, went through all of the defensive meetings, the special teams meetings, workouts and practices everybody else did, but then met with linebackers coach Reggie Herring for two additional hours each day.

"We were meeting two hours a day, grinding it out, a crash course is what I would call it," Nelson said. "Then at night, you'd want to study some more, just a little more, but after practice, the meetings, all of that, sometimes you'd kind of just lay there on the floor like you were dead. This week is better. It's slowing down a little, but you still have homework, you know?"