The Ducks are 6-1-1 to the Under in their last eight games. It's easy to see why. They give up the sixth-fewest goals and score the fewest goals per game of any team. 
John Gibson was one of the hottest goalies in the league coming into Saturday's game against the Blues with a 1.87 GAA and a save percentage of .942. But Gibson had his worst performance of his career giving up three quick goals. He promptly was pulled. I expect Gibson to be back in goal and with a real chip on his shoulder. Same with the Ducks' defensemen who didn't play well either in Saturday's 6-1 loss to the Blues. 
Blues goalie Jordan Binnington is off to a hot start, too, for St. Louis. I'm fine going Under 5 1/2 even if Binnington is rested for this game.
The Under has cashed seven of the last 10 times these teams have met.