Toews is a better all-round player because of his offense, but does anyone really think he's on the same level as Bergeron in terms of pure defense?
Back to the topic (Selke voting):
I see Toews getting an awful lot of Selke votes from voters who prefer to vote for two-way players over more purely defensive ones. Basically, if he has an off-year offensively, I don't see him getting many votes. While Bergeron would still get votes regardless of his point totals (but probably wouldn't get nearly as many in an off-year offensively).
Edit: To add to what I've said, these are Bergeron's last 3 Selke finishes: 1st by a landslide, close 2nd, 1st by a landslide. Here are Toews: 6th, 1st by narrow margin, 3rd.