THIS WAS THE GAME fans circled on the schedule back in the offseason, then underlined when so many of the Eagles' early opponents turned out to be even more hapless than imagined.

The Nov. 1 Giants game will tell us, the keepers of the conventional wisdom solemnly intoned. Then we'll know what kind of Eagles team this is.

Well, Eagles 40, Giants 17, game over by halftime, when the Birds held a 30-7 advantage.

So, whaddaya know?

Well, apparently this Donovan McNabb fellow (17-for-23, 240 yards, three touchdowns, 146.7 passer rating) is not washed up, or hopelessly addicted to throwing passes at his receivers' feet, as some of his critics have implied in recent weeks.

"I guess I was pretty accurate today," McNabb said, smiling.

And the Eagles can, indeed, run the ball, all previous evidence to the contrary be darned, 180 yards yesterday on 24 carries against a Giants interior line that acted as if it feared the ballcarrier might be transporting swine flu, along with the pigskin.

The Eagles, tied for the league lead with 18 takeaways going in, added three to that total, somehow turning Eli Manning into Jake Delhomme right before our eyes. Covering tight ends is still a problem, but it isn't looking fatal for a defensive unit that two games in a row now has gotten significant pressure without all-out blitzing.

"It's huge," defensive coordinator Sean McDermott said. "You can't blitz every down, and fundamentally, you've got to be able to play the pass without blitzing, and play the run without blitzing."

Definitive statements about the season still seem difficult, maybe because there are nine games to play, maybe because, when all that date-circling occured, we thought we knew what sort of yardstick the Giants were, and now that they've gone from 5-0 to 5-3, we're less sure.

We know the Eagles are 5-2, 2-0 in the NFC East, and now, in addition to losing a game (Oakland) most fans thought they would win, they now have won a game a lot of fans thought they would lose. Their season is on course, the chaos along the o-line and at middle linebacker subsiding. Yeah, they still lost to the Raiders and got blown out by the Saints, but they have recovered, and progressed, heading into a home game Sunday night against the similarly resurgent, 5-2 Cowboys, winners of three in a row.

"That was by far the best game we've played this year as a football team, and I'm proud of our performance," corner Sheldon Brown said after the most lopsided Eagles victory over the Giants since a 24-0 game at the Vet back on Dec. 1, 1996. It was the first regular-season loss for the Giants at Lincoln Financial Field since the 2004 opener.

"I was proud of our guys for battling after a short week," Eagles coach Andy Reid said.

Reid said he elected to sit Brian Westbrook even though Westbrook's neurological testing went well at the end of the week, and Westbrook exercised Friday without his concussion headache from Monday night's victory over the Redskins returning.

"I kind of took a cautious route," said Reid, who didn't let the absence of his franchise back keep him from exploiting what looked like a mismatch up front.

"We wanted to get the matchup of our line against their line," rookie running back LeSean McCoy said after unfurling a 66-yard TD jaunt that set the final score, with 14:22 left. "On tape, we thought our line would have an advantage today. We thought we could be successful with the run."

It had been 17 years since the Birds had scored 40 or more points on the Giants - Nov. 22, 1992, a 47-34 win.

"We're not doing anything well on defense," Giants linebacker Antonio Pierce said. "It's a complete embarrassment and disappointment. We didn't tackle. We gave up big plays. We didn't cover. We're not communicating . . . We're just a bad defense right now."

McNabb and several other Eagles extolled the benefits of offensive balance. It will be interesting to see if Reid views that as a major lesson from this game, or if he just wanted to run it to keep the Giants' ferocious pass rush at bay, and now he'll go back to throwing nearly every down.

"I think being able to establish the run game and the screen game opens up a lot of things," McNabb said. "Any time there, as a quarterback, where you don't have to throw for 330 yards every week to win the game, it takes pressure off you and it also puts pressure on the defense."

The first sign that the game wasn't going to go according to expectations came on the third play from scrimmage, when the Eagles lined up with two tight ends, fullback Leonard Weaver alone in the backfield. Something unfolded that longtime observers of the Reid regime never expected to see: Weaver took the handoff, rumbled off left tackle and just kept rumbling. Forty-one-yard touchdown run.

It was the longest run by an Eagles fullback in 20 years - since Oct. 8, 1989, Anthony Toney vs. the Giants, when fullback was a different position, really. It was the longest TD run by an Eagles fullback since Earl Gros, in 1964, when just about everything was different.

When the Giants' first drive ended with Asante Samuel running a Manning interception back to the Giants' 10 (Samuel's fifth pick of the season), and McNabb ended up throwing an 17-yard, third-down TD strike to Brent Celek after a holding penalty, we were headed down a path only the most fervent Eagles optimist could have foreseen.

"He was throwing off his back foot a lot," Eagles defensive end Darren Howard said of Manning. "We got some pressure early and we got some points on the board early - it's a little bit of desperation, when you get down a little bit . . . we took advantage of that."

The surprises kept coming. We all know how much Reid loves to run the ball. After McCoy's third-and-1 TD run to forever, the Birds had gained 175 yards on the ground on 18 carries. That's a sparkling 9.7 yards per carry for a team that really has struggled to run effectively, throughout 2008 and for the first six games of this season.

"You look at a third-and-1 run that goes the distance, I don't understand that myself, but I wouldn't be able to comment until I see it," said Giants coach Tom Coughlin, somehow managing to comment while not commenting.

Maybe big-play offense - seen as an enemy of rhythm and continuity last week at Washington - isn't such a bad thing, after all.

It certainly seemed to come in handy late in the first half, after the Giants scored to climb within 16-7 with 1:54 left. Ellis Hobbs ran the kickoff back 39 yards to the Eagles' 46, then, on the next play, McNabb hit DeSean Jackson, 54 yards down the left side for a touchdown, Jackson every bit as open as he'd been for the 57-yarder Monday at Washington.

TV cameras caught McNabb pointing to offensive coordinator Marty Mornhinweg after that one. Details were sketchy, but Mornhinweg thought that play would work if the Giants played Cover 2.

"We run that play a lot, and I cross the field," Jackson said. "So I faked the cross and rode it back out, there was nobody else there, and Donovan made a great throw."

"That was a heckuva call," Reid said. "Donovan was fired up because [the Giants] played it just like we hoped they would play it. Sometimes those things don't work out. Marty had a good feel on it, he and Donovan talked about it, and it was a great job on both their parts. Jackson did a nice job of getting that safety to flip his hips, and he was able to break back off of that."

The Giants, trying desperately to regain momentum, went deep over the middle on second-and-10 from their 30, and Manning overthrew Sinorice Moss. Two plays after Quintin Demps' first career interception, McNabb fired a strike to Jeremy Maclin, triple-covered in the end zone, and it was 30-7 with 46 seconds still remaining in the half. The Eagles had answered the Giants' touchdown with two, in a span of 52 seconds.

"I don't think it was a message to everybody else as much as it was a message to ourselves," Maclin said, 2 weeks after the Eagles failed to score a touchdown against the Raiders. "We can do that against anybody. I think that's what we want to do and I don't think that is the last time we're going to do that."

Or, as Mornhinweg said: "We have a chance to be halfway decent."

McNabb talked during the week about refining his mechanics, but mostly he just seemed more confident, more comfortable in the pocket. There was pressure here and there, a pair of sacks including one where he fumbled, but McNabb seemed much harder to knock offstride than he was against Oakland, or the Redskins.

"He was out there flying around and throwing the ball," Jackson said. "He was pumped up. It was great to see him like that. It was like he was out there during his young days. As long as he plays like that, he's unstoppable."

What suddenly clicked? Who knows?

"During the game, I told him, 'You're hot. Stay hot,' " Mornhinweg said. "That's a good coaching point, right?"

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