The most useful nugget of info from Travis Yost's article on TSN a couple days ago is this chart:
Of 128 playoff teams (or in playoff position for this year), the vast majority had positive Corsi ratios. It looks like about 38 made the playoffs below that line. So good Corsi teams make the playoffs just over 70% of the time. Only about 18 of those did so with bad possession ratios, but that is still 14%
What that tells us is that overall, what the Flames are doing is an exception, but not necessarily exceptional. And advanced stat people should probably take that to heart. Predicting that we can't keep it up indefinitely is fair. But analytics guys should not act so offended because Calgary is bucking the trend. By the same token, anti-stats people shouldn't be offended that people don't think it will last indefinitely.