Because of Erik Karlsson. Besides him and Methot (who is injured and probably gets traded if they don't sign him) the defence is awful and post bad possession numbers, Ceci might take a step forward but Jared Cowen and Chris Phillips can't get the puck out of their zone and the former gives up a ton of shots in the home plate area which has a high correlation with goals.
I think we've moved past the team will be better because they had a low point total. Almost every pre season projection I read has Colorado a lot worse because of how unsustainable they were last year.