SAN DIEGO - Little loss, big loss.

The little loss for the Eagles was yesterday's 31-23 setback to the potent San Diego Chargers, an entirely predictable result, given the way the injury cards fell for the visitors. (And the way their offense came up small in the red zone early, when it had a chance to make this a genuine Old West shootout, instead of a rout in which the home team got a little sloppy. But that's another story thread we'll pick up later.)

The big loss was Brian Westbrook, standing on the sideline from the third quarter on in a baseball cap, having suffered another concussion - a blow that certainly puts into doubt Westbrook's season, if not his career. Deepening the big loss was the departure of cornerback Sheldon Brown to a hamstring injury that Brown said would be MRI'd today.

The fact is, you can get to the playoffs from 5-4 - the Eagles did it last year, even after 5-4 become 5-4-1 at Cinncinati and then 5-5-1 in a debacle at Baltimore. But can you get to the playoffs with this injury situation?

After the Birds furiously worked their way back from a 28-9 deficit at the start of the fourth quarter to 28-23 on a Brent Celek touchdown catch with 7:12 left, the Chargers kept custody of the ball until they kicked a field goal with just 30 seconds left. As the Eagles' chances bled away, it seemed as if every crucial throw went at either corner Dimitri Patterson, the little-used special-teams guy replacing Brown, or Ramzee Robinson, the corner who got thrown into the fire on his fifth day as an Eagle.

Robinson, released by the Lions in the preseason, was signed when Ellis Hobbs went down for the season with a neck injury last week, just as Joselio Hanson was being suspended for 4 weeks for taking a banned diuretic. He was offside when the Birds stuffed Darren Sproles on third-and-2 from the Eagles' 25, keeping alive the drive that produced the difference-making final Chargers' touchdown.

"I saw some young guys in there playing that I thought did some good things,'' Eagles coach Andy Reid said after his team lost back-to-back games for the first time this season. "Guys that had to step in there and play and suck it up, and tried their hearts out. But you can't get in the red zone three times early and not be able to punch it in, especially as [close to the goal line] in the red zone as we got. That hurt us in the end.''

If Westbrook can't come back and be effective for the stretch drive, that will hurt the Eagles in the end, as well. They finished with 29 yards rushing - against what had been the league's 26th-ranked run defense - and Westbrook gained 28 yards on just six carries. To be fair to rookie LeSean McCoy (three carries, 5 yards), the Birds pretty much abandoned the run in the second half, when he got all of his touches. Reid will talk this week about how much confidence he has in McCoy, but it wasn't clear McCoy had any role in the gameplan whatsoever yesterday until Westbrook went down, in his first action since he suffered a concussion Oct. 26 at Washington.

An Eagles spokesman told reporters waiting to talk to Westbrook that he would not be available. The Eagles will face questions on their handling of the initial concussion, given that he suffered another so quickly.

"I feel bad for Brian,'' Reid said. "I feel bad for him, and it's something that our doctors will look at and be right on top of it, right when we get back.''

Quarterback Donovan McNabb said the effect of Westbrook's situation on the team was not the main focus.

"We have to understand what's at stake here,'' said McNabb, who tied a career high with 35 completions, in 55 attempts, for 450 yards, only 14 yards shy of his career high. "The head is something you just don't play with. You want him, first and foremost, to be healthy, and clear to be able to go out there . . . while he was in there, he made big plays for us, picked up first downs, picked up big blocks [on blitzes].''

But McNabb also agreed that the Eagles really can't just seamlessly turn the page from Westbrook in the middle of McCoy's rookie season, with the team depending on so many other inexperienced parts.

"Veteran leadership is something we don't have that much of,'' McNabb said. "We're going to call on McCoy to do a lot of different things.''

One of those veteran leaders sounded a call to arms, for a defense that gave up more than 20 points for only the second time this season. The Chargers, who came in with the NFL's 32nd-ranked running game, suddenly remembered they employed LaDainian Tomlinson, and they wore down the Birds with 24 Tomlinson carries for a season-high 96 yards and two touchdowns. Quarterback Philip Rivers, with an effective running game in his back pocket, was a ridiculously efficient 20 for 25 for 231 yards and two more TDs - a 131.8 passer rating. For the first time this season, the Eagles did not force a turnover.

"It's time for the guys to commit to this game and to commit to the teammates and commit to winning, and that happens in practice,'' said strong safety Quintin Mikell. The Birds had linebacker Chris Gocong starting in the middle for the first time since high school, as Will Witherspoon moved to the weakside in place of Akeem Jordan, out with a knee injury. "We had way too many mistakes out there today. We had too many communication-type errors and too many penalties [nine for 70 yards]. You can't have that kind of stuff. When you're playing a good team like this, you need everything you've got.''

The game probably came down to the Eagles' offense, though, and those three drives that resulted in chip-shot field goals instead of touchdowns while the game was within reach.

"When we have these opportunities to score, we have to pound it in there,'' McNabb noted. "We definitely tried, and credit to them that they obviously stopped us from running in the red zone . . . we did fight back in the second half, just ran out of time a little bit, but you can't play games like this; mistakes, penalties, starting late.''

Of course, the Eagles' usual pattern in losses this season has been to start strong and then wither, particularly their offense. Yesterday was kind of the opposite of that. There was hope in between the lines of McNabb's 20-for-31 for 271 yards and two TDs in the second half, with the Chargers knowing the throws were coming. Also in Jason Avant's fierce, eight-catch performance (for 156 yards, the catches and the yardage career highs), and in DeSean Jackson's eight catches for 91 yards on a heavily taped right ankle.

Todd Herremans, thrown into his second career start at left tackle, when Jason Peters couldn't play with an ankle sprain, battled gamely in the pass game, as did the rest of the scrambled-yet-again line - Nick Cole at left guard instead of right, Stacy Andrews starting on the right side for the first time since the opener. But the run-blocking was a jumbled mess again.

Most egregiously, the Eagles had first and goal from the San Diego 1, down 14-0 midway through the second quarter, after Jeremy Maclin was interfered with in the end zone. First down, Leonard Weaver seemed to get the ball late, and was stood up, losing half a yard. Second down, the Eagles tried to fool the Chargers, McNabb rolling left, pursued hard, throwing incomplete to Celek, who was covered. Third down, little-used Eldra Buckley tried to power in. Several Eagles thought he had, but that was not the ruling on the field, and unlike last week Reid did not throw the challenge flag.

Incredibly, Fox showed no replay, instead giving us a dandy graphic that broke the news that the Eagles had also failed in such a situation the week before. Who knew?

"If I did get in, I should have made it clear that I got in,'' Buckley said. "I thought I was in, but it don't matter what I think, man, it matters what the referee thinks.''

"I don't think I did a good job hitting the hole, like I should have,'' Weaver said. "The o-line did their job. I just didn't get through. They had a couple linebackers come over top, and it's my job to get through 'em. I didn't do it.''

David Akers kicked an 18-yard field goal. Similar 25-yard consolation prizes arrived at the end of the half and the second drive of the third quarter, before the Chargers scored their fourth touchdown, and their defense relaxed a little.

For more Eagles coverage and opinion, read the Daily News' Eagles blog, Eagletarian, at www.eagletarian.com.