The article title was that they came on strong in Ontario, specifically.  There's nothing remotely surprising about Tory candidates doing well in Calgary ridings that were barely contested.

There isn't any need to "explain the results" there.  By-election voting percentages have no particular predictive track record; Yvonne Jones got 47% in a 2013 by-election in Labrador, and then got 71% running against the same guy in 2015.  A fluctuation of a few percent is noise.