This is not definitive, but the Flames have an expected goals for of 63.43 (4th best) and have scored 58 goals. Thus, according to this model, the Flames have scored a little more than 5 less goals than they should have. This suggests the Flames may have a slight finishing problem this year, but its nothing compared to a team like the Hurricanes, which has an expected goals for of 72.7 and has scored 49 goals.
Meanwhile, the Flames have an expected goals against of 53 (18th best) and have allowed 58 goals.
So that's a goal swing of a little more than 10. Also, I just wanted to add the Flames expected goal differential of 10.43 is 4th in the NHL behind the SJS (10.49), LVGK (13.87), and CAR (24.85(!!)).
http://corsica.hockey/team-stats/