Coach Jack Pardee, evaluating the Redskins on the last day of training camp, admitted today he could not predict how successful the club would be this season until he sees 'whether Wilbur Jackson and our new backfield work out."

Pardee said Washington, which plays Oakland at 7:30 Saturday night in an exhibition game at RFK Stadium, is "improved over last season." But, he added, "The fact we are starting a new halfback and a new fullback fits into the category of a monumental change.

"How would Dallas or Houston or Philadelphia be if they started a new backfield from last year? It's a major move. This will be one of our big tests, no doubt about it."

Jackson, who was obtained from San Francisco Thursday, is projected as John Riggins' replacement at fullback while Riggins continues his contract holdout. Buddy Hardeman, a third-down specialist last year, has moved into Benny Malone's starting halfback position.

"If we can stay even or get better in the backfield, that will have a lot of influence on our season," Pardee said. "It will go a long way toward determining our success.

"Wilbur has to be a good player for us. But we still have to get more backs involved in the running game this year. We think he can gain 1,000 yards, but if he doesn't, maybe we can have the same success if he gets 800 and we have halfbacks contributing more yardage than last year.

"Who knows? Wilbur might even make us better, because John was more of a one-dimensional back than he is. But I'm convinced that even if Riggins doesn't come back, now we can survive and possibly be stronger."

Jackson arrived in camp today and dressed for the afternoon workout. He may play briefly against Oakland.

"We'll give him a little work if he feels he can handle it," Pardee said. "But we don't want to rush it too much." Pardee said otherwise he would go with the club regulars for three quarters before beginning any mass substitution.

"I want to get some continuity and give our starters and situation people a lot of hard work," he said. "Then we hope to be in a position where we can use them as we want in our final pre-season game."

As optimistic as Pardee has tried to be during the Riggins holdout, the Washington coach said today that the walkout "took the edge and excitement off this camp. It's been one of the best camps I've ever been involved in as far as getting things done. But it's also been disruptive."

And until the Redskins traded for Jackson, Pardee admitted he was very concerned how he would juggle things well enough to give the club a chance to have a successful season.

"We still have a whole lot to prove," he said. "But we have a chance now (to be good). We have to go out and prove we can win; that's the bottom line.

"Until we've proven to ourselves that our offensive backfield is completely set, I don't know how far we can go. I do know we are a good team. I like our matchups against mostly everyone. We'll be okay, barring any more disasters."

Pardee has taken steps this week to shore up another potential trouble-spot.

He has begun using guard Fred Dean at tackle in hopes that Dean possibly will emerge as the No. 1 backup player at that spot behind starters George Starke and Terry Hermeling.

Dean, who was the club's reserve guard last season, has been starting at guard in the preseason for the injured Jeff Williams. He will play guard and tackle against Oakland. Pardee also will take another look at tackles Mike Gibbons and rookie Jerry Scanlan.

The switch of Dean could have a great effect on the close competition at guard. Pardee said that Dean was running ahead of both Dan Nugent, coming off back surgery, and young veteran Gary Anderson in the battle for the backup guard position. If Dean moves permanently to tackle, then that would change the reserve guard situation.

Other than the backfield question, Pardee seemed pleased with what he has seen throughout the five-week training period.

"This is a team with a little more confidence than a year ago. They know more about each other. The team a year ago had to find out about a lot of new guys playing key positions but all those guys are now part of our foundation.

"We are closing the gap on the rest of the league. Last year, Cleveland manhandled us in the preseason. This year, we felt bad because we didn't look good beating them. Last year, we had a lot of doubts after that game."

According to Pardee, linebacker Monte Coleman had probably the best training camp of any Redskin. And he ranked Mike Nelms, the backup free safety and No. 1 punt returner, as the biggest surprise.

Nelms was signed by the Redskins after playing three years in Canada.

Pardee said that Art Monk, the No. 1 draft choice, has strengthened the receiving corps. "I look upon that area the same way I did linebacking last year," he said. "The linebackers changed from a weakness to a strength overnight. That is eventually going to happen with the receivers.

"We also have had a heck of a free-agent bunch. People like Kevin Turner and Chris Godfrey and Jerry Scanlan and Zion McKinney and Ricky Claitt all have done something good."

The work of the free agents makes up for the failure of the club's draft choices. Only Monk and No. 2 Mat Mendenhall remain from eight picks.

Oakland will bring a 1-1 preseason record into the Washington (2-0) game. The Raiders have a new quarterback, Dan Pastorini, who was obtained from Houston in exchange for Kenny Stabler, and possibly a new starting running back, Kenny King, who came from Houston for safety Jack Tatum.

The Raiders should give the Redskin defense which hasn't allowed a touchdown, its best test so far. Pastorini loves to throw long and, in Cliff Branch, he has one of the game's swiftest receivers.