ANDY REID was furious. Referee Scott Green had just cost the Eagles four points because of a roughing-the-passer call that he had made on defensive end Jason Babin, prolonging an extinguished drive. What should have been a Chicago Bears field goal in the last minute of the first half ended up being a touchdown because of that flag, and Reid was chewing out Green in a way that you rarely see: pointing, gesticulating, the anger shooting from his eyes.

Because that is the thing about this Eagles defense - and Reid has to know it as well as anyone. That is, the margin for error is so small, still.

"I think it's a really frustrating loss because what we did out there, and some of the circumstances, makes it a little hard to swallow," Babin was saying, after the Eagles coughed up another fourth-quarter lead and lost to the Bears, 30-24.

"There were some calls that went the other way that played into some field-position changes and some scores - but you can't blame it all on a couple of bad calls. We definitely did it to ourselves."

It was a debatable call against Babin, to be sure. The hit on Bears quarterback Jay Cutler was a little bit late, and that was true enough - but Babin did appear to be shoved from behind by the Bears' Chris Spencer.

Pushed, Jason?

"I got launched into the quarterback," Babin said. "But I don't think I pleaded my case very nicely to the referee. I more charged him. I was little upset about it at the time. That's the way it goes.

"That whole thing - the fumble [by DeSean Jackson on a punt return], we stop them on third down, then throwing the flag - that was huge. That was a big score."

It was a play that the referee might have chosen to ignore in many circumstances. But Green didn't, and Reid was wild. An advantage had been squandered - and we all have learned that if the Eagles don't have a really big lead in the second half, or the generosity of Rex Grossman to bank on, there is trouble.

It is the story of this season, a defense that cannot be counted upon. They had come off a good game against the Washington Redskins and a great game against the Dallas Cowboys - proving, perhaps, that the NFC East really isn't very good this year. They had played those games, though, and they were beginning to develop a little bit of a swagger, and then they found themselves last night on the wrong end of 30-24.

They blew another fourth-quarter lead, allowing the Bears to score 13 unanswered points at the end. It was their fourth blown fourth-quarter lead of the season and their third at home. The Bears often kept extra people in to block and, for the first time all year, the Eagles didn't have a sack. And when Michael Vick couldn't pull out the game at the end, the Eagles were left with a 3-5 record and all kinds of issues once again, starting with the fact that they are three games behind the New York Giants in the standings.

They have a run defense that aspires to be adequate and nothing more; Matt Forte and Marion Barber combined for 164 yards on 33 carries. They are using a nickel cornerback, Dominique Rodgers-Cromartie, who was having a really rough game against the Bears. At one point in the fourth quarter, after defensive coordinator Juan Castillo said something to Rodgers-Cromartie, the player stomped off, waving his arm in obvious disgust and needing to be calmed down, first by teammates and then by Reid.

"The offense, I think, played good," Babin was saying. "They gave us enough juice to win. Defense, we let them put those drives together late in the game.

"I thought, going into halftime, we had the momentum. Defensively, we had things clicking the way we wanted to. They came back and put some nice drives together and got the momentum back."

Since 2008, the Eagles are second in the NFL in takeaways. It has to be their game, and there really is no way around it. They are not built to smother opposing running backs as much as they are built, ideally, to control them. They are constructed with speed as the first variable and everything else coming after that - speed to rush the passer, speed to cover on the outside. The middle of the field is left to take care of itself.

Their game has to be speed and turnovers - and while they did force two Bears fumbles, all that got them was a stalemate on the giveaway-takeaway chart. If they don't win there, and if their pass rush is not dominating, it is not enough.

"We've just got to find a way to put it all together on a consistent basis," Babin said. "Because if we don't, we're going to be in the same position."

That is, wandering in the wilderness.