There's an old saying in sports that says "defense wins championships". No matter how many goals the offensive powerhouse scores, the team who plays solid defense will usually win out.
Team defense is extremely important in all sports, and that definitely includes hockey. Teams like the Nashville Predators and Montreal Canadiens got to where they are at this point in the season due to good, old fashioned defense.
Here is a ranking of the defenses of the 16 playoff teams.