we gave up 34 to the giants. Thats equal to giving up 45 to a real team.
The Giants defense scored 1 TD.
The Cowboys defense scored 1 TD.
That alone puts the defense points allowed at:
Cowboys 27
Giants 30
Each defense should have the points they scored deducted from how many they gave up:
Cowboys 20
Giants 23
Then the offense gave the Giants the ball with 17 yards need to score. That's a guaranteed 3 points meaning at most the defense it to blame for 4 points.
Effective Points allowed by Defense:
Cowboys 17
Giants 23