ARLINGTON, Texas - Seasons come down to games in the NFL, and games come down to plays, and plays come down to seconds, and sometimes slices of seconds. And there we all were at AT&T Stadium yesterday, slicing seconds deep into the night.

Could the Eagles' season really come down to this?

With 2 minutes left, the Eagles were punting the ball away to the Dallas Cowboys while only holding a two-point lead. It was not supposed to be this way. The Eagles were a touchdown favorite on the road against the Cowboys and their backup quarterback, Kyle Orton. This was to be their moment, their statement that the NFC East was going to belong to them, not just in coach Chip Kelly's first season as coach but into the future.

The statement was supposed to be as loud and as bold as the Eagles' offense has been all season. That was the expectation. That the NFL routinely crushes expectations like soft fruit was barely acknowledged.

But there they were, punting - punting and hoping that the defense could hold. It was 24-22 and the building was in full roar. It was 24-22 and the loser was going home for the winter.

And then it happened. With 1:43 left, Orton made the big mistake. He threw behind receiver Miles Austin on a pass over the middle and Eagles cornerback Brandon Boykin stepped up and made the interception that effectively ended the game and put the Eagles into the playoffs.

They are NFC East champions in Kelly's first season. They are there, in large part, because of a defense that couldn't stop anybody in the first month of the season. They are set for a Saturday night matchup at Lincoln Financial Field against the New Orleans Saints. They have already done more this year than any of us expected, or had a right to expect.

It will be remembered, whatever happens, as an undeniable success. If the Eagles ever get their hands on the Lombardi Trophy, it will be recalled with fondness as the springboard for a franchise.

But will they all remember that they spent almost the entire night just waiting to exhale?

Well into the fourth quarter, and the Eagles were leading by only a sliver, by 17-16. Quarterback Nick Foles had already lost a fumble in the third quarter that gave Dallas three points. The Eagles had cost themselves more points later in the quarter when Foles was stopped on a quarterback sneak from fourth-and-goal at the 1. And the whole thing was just hanging there, with neither Eagles line winning the battle and Orton refusing to make the killer mistake.

Then the Eagles went to their running game in an attempt to create some breathing space. The drive ended up being 11 plays long. The Eagles ran on nine of the plays. LeSean McCoy, who earlier in the game broke the franchise's single-season rushing record, did the heavy work and Bryce Brown got the glory, the 6-yard touchdown run with 6:09 remaining. That put the Eagles ahead by 24-16. It re-established some semblance of order - for about a minute or so.

Because, just like that, Dallas scored again - on a 32-yard pass to Dez Bryant, a play where Bryant slipped a tackle by Eagles safety Patrick Chung. The Cowboys went for the two-point conversion, but the pass was incomplete to Bryant. If it hadn't been, they still might be playing.

The whole night was like that, just incredibly uncomfortable. At halftime, the scoreboard said the Eagles were leading by a touchdown, 17-10. There was unease in the number, understandably. There was no denying that Orton, filling in for the injured Tony Romo, was better than anticipated. In the first half, the Eagles never touched him - literally. The pass rush was timid, blitzing was ineffective, and Orton proved himself a professional who could stand in the pocket and deliver the ball when given time. And, at the same time, the Eagles were having trouble protecting Foles at their accustomed level.

The truth was, the difference in the game was two turnovers that had linebacker Mychal Kendricks' fingerprints all over them. The first was a forced fumble, when teammate DeMeco Ryans shoved him into Dallas running back DeMarco Murray. The second was an interception of a pass, thrown behind tight end Jason Witten, that clattered off of Witten's hands and into Kendricks'.

But then, as the third quarter unfolded, the unease about the Eagles grew. It was there until the end - building, suffocating unease.

It was there until Boykin made Orton pay for that final mistake.

On Twitter: @theidlerich

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hofmanr@phillynews.com