The Eagles needed their defense to be better today than it was a week earlier, and it was.
Put into some tough spots by the offense and by coach Andy Reid, the same group that gave up 500-plus yards and 38 points to the Giants responded with some big plays of its own. Some of that is a credit to rookie coordinator Sean McDermott, some of it to the players and some of it, to be honest, had to do with the opponent.
Add Alex Smith to the list of self-immolating quarterbacks the Eagles have faced this season. Beating Smith, Jay Cutler, Jason Campbell and Matt Cassel is not quite the same as shutting down Drew Brees or Brett Favre.
"They don't have the offense the Giants have," linebacker Jeremiah Trotter said of the Niners.
The schedule makers who gave the Eagles Tampa Bay and Oakland can't help them come playoff time. Smith and Cutler aren't going to be across the line of scrimmage in January. Brees or Favre may well be.
With an offense as versatile and powerful as anything we've seen during Reid's tenure - this group may be even more explosive than the 2004 offense, which is saying something - the Eagles' postseason fortunes likely will rise and fall with the defense.
The death of coordinator Jim Johnson last summer created a void. There's just no way around it. McDermott has filled in better than anyone had a right to expect, but he has had to deal with injuries at linebacker and some truly egregious lapses in such fundamental skills as knocking down the man with the football.
That was the story last week, as missed tackles turned a couple of routine passes into long touchdowns for the Giants.
"We looked at the tape and it wasn't as bad as it seemed," Eagles defensive back Sheldon Brown said. "We had to focus on tackling a little better and eliminate some big plays, and that's what we did tonight."
Fair point. But the big numbers, in yards allowed as well as points, represented a crisis for McDermott and his players.
"This was a big week for everybody, not just Sean," Trotter said. "He's the coach, but we're the guys who were on the field. We came out and played well."
It is not the Eagles' fault the Niners weren't a better test, although Frank Gore is an elite running back and Vernon Davis is a weapon at tight end. The Niners also got quite a bit of help from the Eagles' coach, offense and special teams.
Reid started it with the mind-boggling decision to go for a fourth and 1 at his own 29-yard line in the first quarter. It was, like his onside kick to open the game against Washington a couple weeks ago, an impossibly ridiculous thing for a coach to do. All it did was give a mediocre team a chance for easy points.
Actually, this mini-coaching clinic started a play earlier. Reid ran Michael Vick out there on third and 1. Vick couldn't get the yard. Donovan McNabb was slow to return to the huddle, forcing the Eagles to use a time-out. Even with the extra time to rethink what he was doing, Reid went for it. Leonard Weaver was stuffed trying to run off left tackle and San Francisco got the ball 29 yards from the goal line.
Brown saved the coach's ample bacon, forcing a fumble that Asante Samuel recovered.
"When Big Red calls the shot, we've got to back him up," Trotter said. "We were able to get a turnover there."
When McNabb threw an interception in the end zone late in the second quarter, Tracy White picked off a pass and gave the Eagles a chance for a field goal.
After the special teams allowed a 54-yard return on the opening kickoff of the second half, the defense held the Niners out of the end zone. It took another McNabb interception - giving San Francisco the ball in Eagles territory again - for the Niners to get into the end zone.
"We still have a long way to go," Trotter said. "Great teams don't hurt themselves. But we only gave up one touchdown, which I don't think we should have given up."
Josh Morgan broke a couple of tackles on the 12-yard score, one of several plays where poor tackling was an issue again. For the most part, though, the Eagles played solid defense, pressured Smith, and created enough turnovers to secure the win.
The Eagles have enough offense to win a shoot-out with the Saints or Vikings in the playoffs. They don't need great defense - not in this league, not this year - but they do need good defense.
They got it today, with a little help from Alex Smith.