Eli Manning sat down to watch videotape of the recent loss to the Panthers, and to do that, he had to scroll through a number of options on the computer screen to select the game he wanted to view. And that was when it really hit him.

“You just go down each one, starting with Dallas, and how many opportunities we had and how many games we lost on either the last play of the game, on a field goal made or a field goal missed, or on a play within seconds of the game being over and how many close ones there are,” Manning said of the agony of reliving all of the tough losses when they were set out before him, a menu of misery from which to choose. “I feel like every game has been that way. Every game we’ve had an opportunity. We’ve had a lead and lost it, or maybe we were behind and fought back and just ran out of time.”

As the Giants head into the final days of their regular season, and as 2015 plays out its waning moments, it’s natural to look back on the year that was for the Giants.

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Six of the Giants’ eight losses have been by a combined 15 points; seven have been by a combined 21 points. There were so many games that felt like punches to the gut — some of which, as Tom Coughlin noted last week after the latest misfortune, felt as though they landed a bit lower — that they tend to blend together.

But the one that sticks out still, even 3 1⁄2 months later, is the opening-night loss to the Cowboys. That game set the tone for the entire season with poor decision-making, a defensive collapse and a mind-boggling loss. They’ve dragged it around with them ever since, a burden weighing them down as they trudged through the 13 games between then and now.

In the world of “what ifs,” that game undoubtedly stands as this team’s biggest regret.

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“If we would have won that first Dallas game, what would have happened?” cornerback Prince Amukamara asked when presented with that thesis.

It’s a fair question. And the answer is startling.

First, let’s say they won that game and every other game went the exact same way it did. The Giants would head into this weekend tied for first place in the NFC East at 7-7 and could not be eliminated until Week 17 at the earliest.

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The weight of that game, though, is even more significant when it comes to potential tiebreakers. Even with the same overall record they have now, had the Giants beaten Dallas in the opener, they would win any potential tiebreaker with Washington, Philadelphia or both.

“I never even thought about that scenario,” Amukamara said.

But that’s just the effect of a single victory, or exchanging it. It does not take into account what it would have done for the Giants’ confidence, attitude and success moving forward. If this season had a Butterfly Effect moment, it was that flap of the wings in Dallas that set everything else in motion.

“You look back over some of the closer games we had a chance to win, especially some of the division games, of course they hurt,” linebacker J.T. Thomas said. “Of course they are affecting us right now. But we can only control the controllables, man, and that’s our preparation for this Sunday. One can go back and say, ‘What would have happened here? You guys get off to a better start?’ But right now, man, the cards are what they are. They’re dealt how they’ve been dealt.”

Let’s recall exactly how the Giants lost that fateful, tone-setting game. They were up 23-13 with 8:01 remaining. Dallas drove for a touchdown to close to 23-20, slicing through the defense for 76 yards in 2:53. Then the Giants drove to the Cowboys’ 4-yard line — and things began to unravel.

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Manning lost track of the number of timeouts Dallas still had. He told running back Rashad Jennings not to score a touchdown if the Cowboys allowed him to, which they did not do. On third down, Manning rolled out and threw an incomplete pass rather than taking a sack to keep the clock running. The Giants had to settle for a field goal to go up 26-20 with 1:34 remaining instead of either 30-20 with the benefit of a touchdown there or the same six-point edge with well under a minute remaining had they not obliged the Cowboys and stopped the clock for them.

Then Dallas drove 72 yards for the winning touchdown with seven seconds remaining.

It was one of the most difficult, embarrassing, soul-grating endings to a game in the past five seasons for the Giants. And everything since that point has been, well, kind of the same.

“I think there have been so many games like that where at the end of the game, we’re like one score, one field goal, one point away,” said guard Justin Pugh, too polite to throw in being one defensive stop away. “It’s been something that has become kind of sickening to look back and know how many close games we have lost. I don’t even know the number, how many there are, but I know that we’ve been in every single game, probably, besides Philly [which they lost, 27-7, in Week 6]. We easily could have a flipped record or have 10 wins, 11 wins. But we don’t.”

Want further proof of how that loss in Dallas weighs on the psyche of this team? Odell Beckham Jr. was talking about that loss a mere half-hour after last week’s loss to the Panthers, a game in which he was involved in a series of high-intensity, suspension-worthy plays and the Giants erased a 28-point deficit, only to lose on a field goal as time expired.

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“Coulda, woulda, shoulda,” he said about dropping an early touchdown pass, about that loss to the Panthers, and, really, the entire season. “We could have scored the first week in Dallas and could have won the game. There’s many balls I could have caught. I don’t think about coulda woulda shouldas.”

Yet it was brought up, unsolicited, by the team’s biggest star.

Many Giants insisted they are not yet at the point where they are breaking down the path this season has taken. They are focused on the Vikings on Sunday night, the Eagles next week, and whatever lies beyond that.

“If we looked back on everything, every single thing this year that went wrong or right, we wouldn’t be able to truly prepare how we should,” Thomas said. “This is no time to worry about spilled milk or water under the bridge.”

Added Pugh: “You can’t keep looking back on the past. We have to go out and finish these last two.”

Maybe they will. Maybe two wins will get them going in the right direction, salvage jobs on the coaching staff and front office, allow them to reach .500 and head into the offseason with a bit of momentum.

Or maybe they won’t.

No matter how this season ends, though, there’s a strong chance that the most significant game on the schedule will not be either of these last two. It will be the first one, that night in Dallas, the one in which the Giants unraveled — the loss that they have not been able to truly regroup from since.