If you're a realist, you don't have high hopes for the Rod Marinelli's defense. And if you're a realist, the defense played decently well in the season opener. Again, "played decently well" is relative when you consider the low expectations.
By the numbers, the Cowboys forced one turnover and sacked Eli Manning twice. Benson Mayowa, who the Cowboys signed away from Oakland, picked up a sack during his Dallas debut and Orlando Scandrick secured the other one. Of the current Cowboys on the roster, Scandrick leads the team with 10.5 career sacks.
The Cowboys gave up 20 points and 316 yards, which is good. However, when you look deeper into the numbers you'll find that they were only on the field for 23 minutes. Point is, they were just "OK" when they were on the field.
The entire game felt like 2014 all over again. The offense was centered around ball-control and converting 3rd downs, while keeping the defense off the field as long as possible.
What should bother Marinelli most is the final minutes of the game. The Cowboys knew the Giants were going to run the ball in an effort to run out the clock, and they didn't do a good job stopping it. Additionally concerning is that the Giants have one of the worst rushing attacks in the league.
That being said, if the Cowboys defense is only going to give up 20 points a game, they'll take it.