ASHBURN, Va. (AP) — Trent Williams and Paul Richardson are pretty sure.

Jay Gruden and Jordan Reed understand there's no way to know.

After the Washington Redskins' starting offense didn't take one snap together as a complete group during the preseason, there's reason for both apprehension and optimism going into their season opener Sept. 9 at the Arizona Cardinals.

On one hand, there's zero evidence new quarterback Alex Smith and his full complement of options will gel in time, and yet there's the thought of limitless potential when tight end Jordan Reed, third down back Chris Thompson and receiver Jamison Crowder are back in the mix.

"We never know," Reed said. "You never know how it's going to go. All you can do is control right now, and right now we're putting in the work to be successful come Week 1."

Because the exhibition finale Thursday at Baltimore will almost certainly feature a matchup of the backups, the preseason wraps up with Smith and the first team putting up 151 yards and two field goals on 36 plays over five series.

Thompson and Reed never took a snap as they work back from offseason operations, Crowder was bothered by a groin injury and Williams saw only limited action coming off knee surgery.

Gruden conceded there's a bit of concern not knowing how those players will handle being reintroduced to full-speed games.

"Just seeing what kind of shape they're in," Gruden said. "Some of the guys like Jordan and Jamison, they missed quite a bit of time. Chris has been getting a lot of work running and all that and I don't feel too worried about him. You're talking about your key weapons not getting a lot of playing time and that's a little bit concerning, but since it is Jordan and Jamison, both are very quarterback friendly and I think Alex will adapt fine."

Williams said "of course, no doubt," when asked about the offense being able to click once everyone is on the field. Richardson, signed in the spring to give the passing game the kind of speed it has lacked since DeSean Jackson left, is downright itching to see what the offense can do when finally together.

"That's why I don't have no doubt in our offense at all: We've been able to execute at a high level," Richardson said, citing the second preseason game against the Jets.

"We're able to operate with guys that aren't the starters. That just makes us more confident for when we get our first string in there that we're going to be able to move the ball even more. We're going to be able to execute more, and we're going to score more."

Washington ranked 16th in the NFL in offense and scoring offense last year — but that was under Kirk Cousins, without veteran running back Adrian Peterson and amid injuries that derailed the season.

Smith was up and down in the preseason and is cautiously hopeful about the offense's upside while acknowledging the Redskins will have to try to put up points no matter who's on the field.

"Any offense is going to be better with all the weapons out there, of course," Smith said. "Hopefully we'll have them all out and ready to roll. I'm hopeful for that. At the same time, whether that's the case or not, we're going to kick off and we're going to play."

The game snaps haven't been there for the first-team offense, but Richardson and Reed find confidence in the practice time that will continue to accumulate before the regular season starts.

Gruden will have to wait and see how players handle getting hit by Arizona defenders, though learning the playbook and work in practice should ease fears about developing chemistry.

"That's what practice is for: for us to get reps together and take advantage of the reps," Reed said. "And that's what we've been doing for the most part. We can see how things are gelling in practice and manifest it on Sundays."

Until that happens, there will be doubt. Williams pointed out early in training camp that everyone is optimistic around the NFL when each team is 0-0, so it's no surprise some of that is flowing for a new-look Redskins offense that has much to improve on.

"I think we're going in the right direction," Richardson said. "Guys are just not where we need to be yet. That's why we continue to drill in practice, we continue to work in practice, so we'll be prepared when the lights come on for Arizona."

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Follow Stephen Whyno on Twitter at http://twitter.com/SWhyno .

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