The only argument I've seen is the rankings don't account for back-to-back and three-in-four situations, which obviously have a large impact on any game.
I can't say one way or another if the Flames, with 2 back-to-backs and 2 three-in-fours, are higher or lower than other teams league wide in that regard so far as I don't know if it's tracked anywhere.
A quick glance at the best, average, and worst teams according to ESPN's strength of schedule (SOS column in the OP's link):
Nashville: 1 b2b, 0 3in4
Winnipeg: 3 b2b, 5 3in4
Edmonton: 2 b2b, 3 3in4
Arizona: 3 b2b, 4 3in4
Columbus: 5 b2b, 1 3in4
San Jose: 4 b2b, 8 3in4 (at one point 7 games in 11 days!)
Nashville has faced tough teams but has been well-rested, while San Jose has faced easy teams but with brutal timing.
I know over the course of the season back-to-backs are tracked, but I don't know if anywhere has three-in-four situations counted.
Calgary ranks third easiest in back-to-back situations over this season with 10. Easiest has 9, hardest 19.
http://hockeygearhq.com/nhl-super-sc...iles-team-4989
Just another piece for consideration. How much value all the pieces hold comes down to each person's belief.
*Note, I counted four-in-six situations as two three-in-fours for this purpose. Could be a poor method?