Eli Manning still looks like a kid brother, and he plays like one too, with a floppy, ungainly optimism, like he's chucking a ball to his pet Labrador or something. This makes him fun to watch, even when he's awful. In fact, there's something pleasurably human in his silly, harebrained mistakes. You almost hate to see him grow up and become a "prototype," as he surely will.

The usual dry phraseology of NFL quarterbacks, chilly techno-jargon terms like "efficiency" and "rating" and "per attempt," don't really apply to Manning. They don't describe the occasional haplessness of the 24-year-old initiate, or his fourth-quarter capers, either. No formulaic QB rating can adequately reflect how Manning's throws go whirling overhead like those Secaucus seagulls visible just outside Giants Stadium, some of them on target, and some of them with no visible purpose or direction.

One minute, he's a helpless goof and the next he's an emerging idol. Last week he was a rank beginner against Minnesota, with four interceptions, and this week he's the reason the Giants have viable playoff hopes, after leading them to a 27-17 victory over the Philadelphia Eagles, with two touchdown passes in the final period. Through it all, Manning is amiably self-deprecating, just trying to figure it all out, with a demeanor that earned him the boyhood nickname "Easy E."

"Obviously, I am not where I need to be as a quarterback and as a player, but I am learning and trying to play smart football to put us in a position to win games," he said last week. "Throwing four interceptions is not a good way to play smart football."

A mature Manning could be the difference-maker, the single most important player in the NFC East: the Eagles' Donovan McNabb is likely done for the season, the Redskins' Mark Brunell is uneven and his team is nowhere at 5-5. That means down the stretch it's probably going to be a duel between Dallas's Drew Bledsoe and the kid.

A month ago, only a fool would have predicted that by Thanksgiving Manning would have the Giants in contention for a division title, and even now his mistakes may still undercut his promise. Former Giants quarterback Phil Simms told the New York Daily News: "Before the season started, somebody asked me, 'What advice would you give Eli?' I said, 'It's going to be torture.' "

But with torture has come a tantalizing view of what Manning can become. Not only have the Giants won five of their last seven, in four of those games Manning has thrown for crucial fourth-quarter scores. "Just play smart and try to get into the fourth quarter to try to win it there," he said. Even playing terribly, he fought back to ties against the Cowboys and the Vikings in the final quarter before losing, and he threw the game-winners over the Broncos and the Eagles. No matter what happens in the previous three periods, Manning seems to make the fourth his best, and that's an ominous development for the opposition.

"It's cumulative," Giants Coach Tom Coughlin said. "The NFL is cumulative and he learns from the first snap on and he gets a great feel for the opposition and it shows up more in the fourth quarter than anytime else. That's what you want."

From the spectators' standpoint, it's engrossing to watch Manning learn on the job -- and in some ways it's more interesting than watching a fully developed quarterback like his brother Peyton, who is so marvelously, robotically efficient. Peyton knows everything and sees all. Every play is a surprise to Eli. He even accepts the snap as if to say, "Hey, a ball!"

Take what he did against the Eagles. Manning floundered in the first half, was sacked four times and was held to 51 yards passing. But he answered with an assertive fourth period in which he found Jeremy Shockey and Plaxico Burress for scores, the latter a glamorous piece of improvisation that came just after the Eagles pulled within 20-17.

The play was indicative of his learning curve. Burress and Manning said later it was a risky play, because Manning could have misread the situation and thrown the ball directly to the cornerback. "You just hope that he will be seeing the same thing you are," Manning said.

Burress said: "We've only been playing together for 10 games with the preseason and training camp so we have a lot of learning to do, the both of us. But we're getting the gauge and the feel for one another, realizing each other's talents and abilities and I think he stretches mine a little bit at times to see what I'm capable of doing. I love that about him."

The other thing the Giants love about Manning is his refusal to let things faze him. He responds to on-field calamities with a kind of springy resilience. If he's invariably self-deprecating, he's never self-doubting. After the Vikings intercepted him four times and batted down several other balls, his accuracy was questioned. He shrugged it off with: "I have missed some and that's just part of football. It doesn't bother me." And he meant it, judging by his performance against the Eagles, completing 17 of 26 for 218 yards.

"Eli just continues to play," said Burress. "He really doesn't let too many things bother him as far as different coverages and when the protection breaks down, different things like that. He just continues to play and focus on what he needs to focus on. Even when we don't have a good series on offense, he's coming to the sideline and making the adjustment with the receivers, the backs, and the line. He just continues to work. He doesn't really get down on himself, he keeps playing hard, and that's what I love about him."

Plenty of others might buckle under the varieties of pressure Manning has faced. There is the pressure from the Giants, who went to extreme lengths to get him and made such extravagant predictions on his behalf. There is pressure from the media. Ludicrously, he has already been asked how it would feel to face his elder brother in the Super Bowl. The New York press one week asks him if his progress has "stalled" and the next hails him.

Even Peyton has winced at the glare Eli has played under. "I told him I can help him with football," Peyton said last summer. "But I can't help him with that New York."

Late Sunday afternoon, Eli ambled out of the dressing room looking like he was going to a frat party instead of the playoffs. He wore a button-down shirt under a brown sweater with a collegiate stripe down the arms, brown twill slacks, and suede Hush Puppies. Outside the leaves were crumpling like brown paper, but somehow, in the middle of his fall playoff run, Eli managed to seem young and green.

"I didn't know what to expect this season," he said. "I said I was going to come in and do my best and try to win games. And for the most part we have been doing that."