This report is more emotional than factual, imo.
If you examine it you will notice that it states that it is a Decline In the Rise (i.e. the boom). After all it had to slow down sooner or later for you can not have increases year on year forever. The reaction to the west is that the decline percentage wise is higher there than in the east. Well of course it should be when there is a boom and the east had none, therefore there is more room to recede.

I also disagree on the origin of the slow down. No, I do not have numbers to prove my point just the impression from news etc. I have been reading negative signs in Ontario about housing for over a year. The slow down was, and is, in Ontario due to job losses, hence the trigger. Alberta has just gone over the crest of the boom. Other western provinces are just catching up. That should be obvious.

Just because there is a slow down ( return to some normalcy? ) in the west now is no surprise and no need for apprehension. That is part of normal cycles.

In summary, I think this article was written to hype bank's apprehensions and justify an interest drop by BoC in the next few weeks.