The traditional football formula is this: The team that is leading in the second half calls more running plays, trying to keep the clock moving and the ball out of the hands of the opposing offense. The team that is trailing calls more passing plays, trying to cover ground quickly and stop the clock regularly.

At halftime of Sunday's 16-13 loss to the Oakland Raiders, the Washington Redskins led by 10 points. They did not trail until the final minute, but Redskins Coach Joe Gibbs called only eight rushing plays in the final 30 minutes, one in the fourth quarter.

The offensive line had controlled the line of scrimmage in the first half, and running back Clinton Portis already had 70 yards at halftime. But with the passing game faltering, quarterback Mark Brunell in a funk and the Raiders generating pressure on the quarterback, Gibbs continued calling twice as many passes as runs in the second half, and a vital game slipped away.

Players and coaches were still deconstructing the troubling defeat yesterday, with play-calling and clock management among the lingering issues in a loss that has dampened Washington's playoff hopes. The Redskins (5-5) have dropped five of their last seven games and committed three more turnovers Sunday; their minus-13 turnover differential is tied for worst in the NFL ("It's a total frustration for us," Gibbs said), but is hardly the only cause for concern.

The passing game is regressing as Santana Moss, once the leading receiver in the NFL, has been neutralized for four straight weeks as opponents focus attention his way, since no other downfield threats have emerged. The defense again conceded just enough big plays to lose and a team that appeared to be finding its swagger with a 3-0 start is routinely dropping the kind of tight games that separate postseason clubs from the pack.

"That's what we've been doing since I've been here," linebacker LaVar Arrington said. "It's always close, but not close enough. Until all of us as a whole come together and realize that we can indeed win and start taking the necessary steps and measures to do that, then that'll be what we are: The team that plays hard, and you're going to have to play your tails off to beat them, but some way, somehow, we'll win the game against them. And I think that's kind of like our rep right now, and we have to do everything we can to change that perception of us. And more importantly, we have to change it amongst ourselves."

Washington failed to score an offensive touchdown against Oakland's 24th-ranked defense, and generated only 94 yards offense in the second half. Portis, who fumbled twice, ran only five times after halftime, despite a solid 4.2 average per carry. With Brunell dropping back so frequently, the Raiders could focus exclusively on rushing the passer. Yet Gibbs called all passes in the fourth quarter, with Brunell going 2 for 11. Twice, with the game tied at 13, the Redskins went three and out, with the incompletions taking a total of 48 seconds off the clock on two possessions, leaving the Raiders ample time to march for a game-winning field goal.

"I don't know what the deal was, but we abandoned the run," Portis said. "We abandoned the run -- I don't know what it was. I can't sit here and tell you it was because of the fumbles or it wasn't, but for whatever reason it was, we abandoned the run. I think when we get to go out there and execute our game plan it's hard to beat us. Every time we become one-dimensional we end up losing."

Gibbs said Portis's fumbles had nothing to do with the decision. "We wish we would have rushed the ball more in the second half," Gibbs said, "and because of that we're probably putting a little pressure, too, on our passing game. I think that's a legit point, and it's something we look at."

The offensive line believed it was overpowering Oakland on the ground, but that momentum evaporated in the pass-happy second half. "We felt like we were giving a great effort," right tackle Jon Jansen said of the line, "and were the more physical group -- all the things the coaches ask us to do."

Washington allowed over 30 seconds to expire before the first half's two-minute warning without a play being called, then the Redskins used one of their final two timeouts immediately after a timeout with the clock already stopped, ending up with a 45-yard field goal.

"It was unfortunate," Brunell said. "I think we've done a very good job of managing the clock this year, but we had a little hiccup yesterday going into halftime."

In general, Gibbs takes a conservative approach to such situations and, particularly late in the half, errs on the side of caution. "I'm a big believer and you can pretty much tell what I'm going to do," Gibbs said. "If it's a momentum-swing possibility, I'm not doing it."

Meantime, the passing game was suffering. Like most teams in the last month, Oakland figured if it stopped Moss it could excel, and that again proved to be the case. The Raiders kept their speedy cornerbacks tight, used a safety to double-cover Moss virtually the entire game, and by stifling him (four catches for 53 yards) it in effect shut down the entire offense. No receiver had more than five catches, and the other three wideouts on the roster -- James Thrash (who left with a hamstring injury before the half), Taylor Jacobs and Rich Parson -- combined for 17 yards.

Moss was on pace to shatter Jerry Rice's NFL single-season receiving record after six games, but has been contained in four games since. Moss has averaged just 61 yards over his last four games without a touchdown and has one completion over 30 yards (he had 10 in the first six games).

"It's always going to be hard to keep it going," Moss said, "because teams are going to start watching more closely and paying more attention to it. When they give me that look, when they give me that [double] coverage, hey, I feel like I did my part, because I feel like someone should be open. All we can do is just go with what we see and hope for a better day."

That day will not come easy this weekend. San Diego, and former Redskins coach Marty Schottenheimer, has one of the most potent offenses in football, a 6-4 record in the tough AFC West (Washington is 0-3 against that division) and its own playoff hopes in the balance. Washington cannot afford another loss at home, or to fall below .500 so late in the season.

"We're at a critical part of the season," Brunell said. "I would call it a must win for us to keep our hopes alive. It's been done before by a 5-5 team. Right now, if we make a run and get some momentum we can get in there. Hope is not lost, but we've got to win a football game."

Clinton Portis, who carried 17 times for 70 yards in the first half in Sunday's 16-13 loss to Oakland, rushed only five times after halftime, finishing with 92 yards. Redskins wide receiver Taylor Jacobs watches the ball bounce into the end zone after having the pass broken up by Raiders cornerback Nnamdi Asomugha.