Campbell went 8 for 21 for 83 yards and two interceptions in the 17-9 loss to the 49ers on Sunday. His 10.7 passer rating is the worst for a Raiders quarterback since Ken Stabler posted a 9.9 against Cincinnati in 1975.
"He struggled with some things," coach Tom Cable said Monday. "There were times early in the game where I thought the protection around him was a little shaky but it seemed to improve as the game went. He did some nice things making plays with his feet. But at the same time you have to make some of those plays more often than what we're doing right now."
With starter Bruce Gradkowski's status in doubt because of a shoulder injury and Campbell nursing a sprained left knee sustained in the first half against San Francisco, Cable said third-stringer Kyle Boller could start this week against Denver. Cable said he would likely make a decision on his starter Wednesday.
The Raiders (2-4) acquired Campbell in the offseason to help turn the franchise around. He was benched after six quarters but got another chance when Gradkowski was knocked out of the San Diego game with a separated right shoulder.
Campbell did a decent job in relief, helping the Raiders snap a 13-game losing streak to the San Diego Chargers. But he could not repeat that against the Niners. He drew a 46-yard pass interference penalty on the first play of the game. But even that pass was underthrown and could have been a touchdown if Campbell had hit Louis Murphy in stride.
Campbell completed his first three passes of the game as the Raiders drove inside the 10 on their first two drives. They settled for field goals both times and only got into position to score again once more.
The Raiders did not complete a pass in the second or third quarters and had only three after the first quarter. Two came on back-to-back throws, a short pass that Zach Miller turned into a 22-yard gain followed by a tipped ball that Miller caught with a dive for a 26-yard gain.
That pass was the only downfield throw all day that Campbell completed. Every other pass was caught less than 10 yards down field, including three behind the line of scrimmage.
"I think the plays are there," Cable said. "I think it shows up on film that they were there, but we're just not executing, whether it's a throw or whether it's a route."
Cable said he did not contemplate pulling Campbell during the game. Boller warmed up on the sideline in case Campbell's knee got worse. Boller said he feels he would be ready to go even though he has gotten almost no practice time with the first-string offense since the start of the season.
Boller had a strong preseason for Oakland, completing 26 of 43 passes for 360 yards, two touchdowns and no interceptions for a 102.9 passer rating.
"I've pretty much stayed on top of it over the last six weeks and that's part of your job," Boller said. "Doesn't matter if you're a starter, second-stringer or third-stringer. You have to always be into the game plan and doing just the same things the starter's doing so I don't think I'll miss a beat."
This marked just the latest time the Raiders followed one of their rare wins with a dud. Oakland is 0-7 following wins the past two seasons as every time it looks like they could possibly be turning the corner they revert to their old ways.
They have been outscored by 19 points per game the week after wins, managing just three touchdowns in the seven losses.
"We have to get over that jinx of not winning two games in a row," Murphy said. "We haven't done that since I've been here. It's frustrating. It's happened after every win we've had. We haven't put two and two together."
Cable said he wouldn't be surprised if the team made a trade before Tuesday's deadline. ... RB Darren McFadden missed his second straight game with a hamstring injury. He will test it out again in practice Wednesday with hopes that he will have his usual burst back.