The calendar has flipped to September, and football fans can now see Week 1 peering over the horizon.

It is a welcome sight, given all of the uncertainty that has filled our world throughout this year. But as comforting as the impending NFL season may be, there is still plenty of uncertainty surrounding it as well.

First, how will the games look and feel without the benefit of preseason games? Most fans probably don't see the value in preseason games other than that they mark the beginning of football season, but they hold immeasurable value for players and coaches.

Defensive Coordinator Jim Schwartz admitted as much to reporters Wednesday, saying that there is no true way to replicate live game reps, no matter how much one tries to in practice. Going from practice at the NovaCare Complex to a game in an NFL stadium (albeit a largely empty one) is a big step in a player's progression. Even practicing at Lincoln Financial Field in front of fans has proven to be a hurdle for some young players to overcome.

"Those guys would sort of go to pieces," Schwartz recalled. "Things that a couple days ago they had mastered, all of a sudden they would blow circuits because it was their first exposure to that kind of environment. Same as the first preseason game. Then you saw the players settle down, and they are like, 'Yeah, I got this.' They knew what to expect."

In 2020, those butterflies will have to be calmed during Week 1 of the regular season. But the challenge isn't young players' alone. Even proven veterans will face one, as for most, Week 1 against Washington will be their first game action since the Wild Card Round in January. It does not take a mathematician to tell you that was now eight months ago.

Because of that, every day at the NovaCare Complex has been met with the utmost importance. There is no time to waste. There is no time to lounge. Time is of the essence and time is running out before opening the season against Washington.

"We got to try to let them know that things are going to ramp up, so the urgency is going to have to be at an all-time high," linebacker Nathan Gerry said about his advice to young players.

Fellow linebacker Duke Riley's advice has been to take things day by day. Whether a player is on the practice field or in the meeting room, they should approach it with maximum focus and the intention of being great.

"We practice really, really fast here," he said. "We try to do things game speed-like, but once you're going against other guys, it's just a totally different thing."

For Riley, preseason games served as a bit of a "wake-up call," as it provided him a status report of sorts on what he needed to improve upon before the regular season. Doing that in practice on a daily basis has been different, but Schwartz believes the team, specifically the defense, has responded well. What the Eagles lacked in live reps, they made up for in knowledge of the system.

"From a scheme standpoint, learning standpoint, everything else, we're 100 percent at full throttle with all that stuff," Schwartz said. "I think the guys have really responded well. We've had a lot of walkthrough times. The guys have really taken advantage of that. I don't feel like we've been shortchanged as far as scheme and that sort of thing."

Regardless of how many live reps players have been able to bank, or game-like situations the coaches have been able to create, the ball will be placed on the tee to kick off the 2020 season in 11 days. The teams that are able to adapt quickly to being in real games will more than likely get off to a positive start. The teams that struggle will more than likely face an uphill battle.