It's only one game. A lot can happen over the final 15 games of the regular season.
Here's what I saw:
Wide receivers could be lethal
Victor Cruz made some big plays in his first game in almost two years. He caught three passes on a drive late in the second quarter that ended with a touchdown. Rookie Sterling Shepard made a leaping catch over a defender’s head for the score. His 41-inch vertical leap (better than Odell Beckham Jr.) came in handy.
And when the Giants needed a drive late in the game to take the lead, they went to Beckham on the first two plays for 22 yards. Easy money.
To cap the drive, Cruz caught the winning touchdown by using his experience and savvy.
It was as promising a performance as the Giants could've hoped for from their wide receivers. Beckham did his thing, Shepard flashed incredible promise and athleticism, and Cruz proved he can be a useful contributor. All of a sudden, the Giants' receivers appear to be among the best and most dangerous in the NFL.
After starting last year with a hobbled Rueben Randle and Preston Parker alongside Beckham, the Giants now have Beckham, Shepard and Cruz. This has potential to be one of the best receiving corps
Eli Manning has ever had, if the trio can stay healthy.
Rookies are promising
It's still very early, but it appears general manager Jerry Reese may have hit the jackpot with this year's draft class. The top three picks (Shepard, cornerback Eli Apple and safety Darian Thompson) will basically be playing starting roles.
Apple exceeded expectations this summer and has become the third cornerback. That pushed Dominique Rodgers-Cromartie into the slot for significant snaps for the first time since he was with the Philadelphia Eagles in 2011. Apple had some good moments in the opener, particularly with an open-field tackle on Cowboys tight end Jason Witten.
"I think he was feeling his way early," coach Ben McAdoo said. "He got his feet underneath him as the game wore on. Really competed at a higher level as the game wore on. Just like a lot of young players, they have to feel their way a little bit at times. You play through it, and I think he made some nice tackles as the game wore on."
Shepard scored a touchdown and finished with three catches for 43 yards. He has proved to everybody who has watched since the spring that he's a player.
So is Thompson. The third-round pick out of Boise State didn't start (because he had been sidelined by a shoulder injury), but he split the snaps with Nat Berhe and really shined. Thompson was flying around the field making plays. He'll be starting soon enough, likely as early as Week 2.
Big-money additions are big players
Again, we've seen only one game, but the early returns from defensive end Olivier Vernon, defensive tackle Damon Harrison and cornerback Janoris Jenkins were evident. The three expensive offseason acquisitions were as good as advertised. You could see the talent that made them the Giants' prized free-agent targets.
Jenkins followed Cowboys star wide receiver Dez Bryant around the field and helped limit him to one catch for 8 yards on five targets. Jenkins' off-field study may have been the difference. "[Bryant is] going to try to big-guy you all the time," Jenkins observed after handling the challenge. He said he knew that quarterback Dak Prescott "liked to throw back shoulder, so I was really playing for that."
The approach worked.
Vernon was also among the most dominant players Sunday afternoon. There were times when he manhandled All-Pro left tackle Tyron Smith or Witten. Vernon had three run stuffs near the line of scrimmage, including one for loss, and forced two holding penalties.
As long as Vernon, Jenkins and Harrison remain healthy, they will be seen as an impressive free-agent haul.
Run defense is a strength
Cowboys rookie running back Ezekiel Elliott will have some monstrous days this season running behind that stellar offensive line. But it wasn't an accident that he was limited to 51 yards on 20 carries (2.6 YPC) against the Giants. His longest run was for 8 yards.
That will happen a lot with 670 pounds of unmovable weight in the defensive tackle combo of Harrison and Johnathan Hankins. The biggest difference between this Giants defense and last year's is that this year the defense will be solid against the run. With Harrison and Hankins in the middle and Vernon and Jason Pierre-Paul at the ends, those are four solid-to-great run defenders. As the Cowboys can attest, it's going to be difficult to run against the Giants this season.
"They had some tough interior guys," Elliott said. "They were big on the inside. ... They won a lot at the point of attack."
The Giants are going to win most weeks at the point of attack with that line. Where the Giants appear to remain problematic is in covering tight ends and the middle of the field. That's where Prescott had much of his success throwing the football.
Offensive line can survive
The preseason spooked many into believing the offense would be doomed by a subpar offensive line. The Giants produced only four first downs and 88 yards in the preseason when Manning was at quarterback.
But the Giants moved the ball well enough on Sunday -- even though it was against a weak defensive front -- to issue a reminder that they were able to do some good things with the same offensive line last season. The Giants averaged 5.9 yards per play on Sunday, and ran with some success even late in the game when Dallas knew they would be running. It was encouraging, if not completely convincing.
McAdoo described his offensive line's performance this way: "Physicality and heavy-handed at the lines of scrimmage with some signs of finish at the end of the runs and at pass protection."
In non-coachspeak, that means they played fairly well.