So I ran the numbers this year (spoilered, below). The correlations are as follows:
5v5 Goals For to Points %: 61.8% correlative
5v5 Goals Against to Points %: 73.9% correlative
5v5 Goal Differential to Points %: 82.3% correlative
So 5v5 goal differential is the strongest correlation to team success of any of these stats BY FAR.
FWIW, Flames are 20th in 5v5 GF, 5th in 5v5 GA, 11th in 5v5 goal differential, and 12th in points percentage.