From a logical standoint, I agree with WD's response and that is why I am shocked that good teams as puckline dogs are winning at an unbelievable rate of 78.5% this year.
One criteria I used was simply taking teams that have cummulatively outscored their opponents over the course of the season. There are currently 17 teams that meet this criteria. One example would be the NY Rangers. They have scored 111 goals vs 89 goals for their opponents this year. Total record for the 17 teams is 167 W - 47 l as dogs on the puckline. If you layed an average of -2.00 while getting the +1 1/2 pucks you would be up about 36 units. Laying an average of -220 , you would be up over 29 units.
Never thought this approach would be profitable, but this year it has been very strong.