49ers crushed by Chargers, 34-7

(12-17) 04:00 PST San Diego - --

Every time the 49ers claw their way back near the Earth's surface, they get shoved back down by the bottom of a playoff-caliber team's boot.

This time, it was the Chargers who put the 49ers back in their place, putting another shovel to the back of their head in a 34-7 burial Thursday in a nationally televised game at Qualcomm Stadium.

"When we have an opportunity to take a step, I look for our team, in spite of the setbacks, to really take a step forward," Niners coach Mike Singletary said. "We continue to stumble. It's a shame we missed a great opportunity right there."

When the dirt clods settled, the 49ers (5-9) secured nothing but their seventh losing season in eight non-winning years with no control over their final resting place in the NFC West standings.

They are now 1 1/2 games behind St. Louis and Seattle with two games to play. If the Rams beat the Chiefs and the Seahawks upset the visiting Falcons on Sunday, the 49ers will be officially eliminated from postseason contention in advance of their Dec. 26 trip to St. Louis.

Most indicting, the 49ers have lost to all seven teams they've played who have winning records. All seven losses are also to teams outside the division, which has been the common theme throughout Singletary's three years.

That alone makes it hard to expect them to make any noise even if they do become the first 7-9 team to make the playoffs. "We've got to win games outside our division," inside linebacker Patrick Willis said. "Until we do that, it's going to be tough every year."

Worst yet, the 49ers are regressing as the season wears thin. Early on, they were narrow losers to the powerful likes of New Orleans, Atlanta and Philadelphia, teams they lost to by a combined eight points in the first five weeks of the season.

Their more recent litmus tests have been abject failures. There was the 21-0 loss to Tampa Bay at home, then the 34-16 beating they absorbed at Green Bay two games ago.

Now this, their most lopsided loss of the season, making it three straight times they chased a division win with a blowout loss. The last three non-division teams 89, the 49ers 23.

"Been up and down," cornerback Nate Clements said. "Can't really put a finger on it. It's been choppy the whole season."

The 49ers were overmatched and mismatched in every possible way. No play says it on defense like Vincent Jackson's 11-yard touchdown for a 17-0 lead just before the half.

The Pro Bowl receiver lined up in the slot. He curled around inside linebacker Takeo Spikes, who immediately saw he had no inside help in the zone coverage.

"He beat the weakness in the coverage," Spikes said.

Jackson also did it on the fourth play of the game, using his 5-inch advantage to outjump Clements on a 58-yard snatch-and-score. Chargers quarterback Philip Rivers recognized the single coverage outside and took the shot.

"We knew they would attack us vertically," Clements said.

There was a 13-play field goal drive in the second quarter, when defensive end Justin Smith was ejected for shoving an official. There was a 14-play touchdown drive that consumed more than 8 minutes of the third quarter.

"Our defense was on the field too long," Singletary said.

The 49ers offense did nothing to give them a breather. They had five first downs and 116 yards through the first three quarters. No play personified their exercise in futility like a 4th-and-goal early in the second quarter.

Rookie running back Anthony Dixon was stuffed for a 2-yard loss when no one blocked inside linebacker Brandon Siler. That was one play after Alex Smith's 7-yard touchdown run was overruled because he was inches short.

That came three plays after the 49ers accepted a first down by penalty instead of keeping Jeff Reed's 38-yard field goal.

"It's less than a yard, our offensive line can get that," Singletary said.

All the offensive line got was Smith smashed on six sacks. Smith was 19 of 29 for 165 yards and a meaningless fourth-down interception in the fourth quarter.

None of this left Smith feeling like the 49ers were a postseason team. "To be honest, when you walk away from a beating like that, it doesn't feel good," Smith said.

After a season of getting beaten up like that, Smith and the 49ers would know.

E-mail David White at dwhite@sfchronicle.com.

This article appeared on page B - 1 of the San Francisco Chronicle