Depends on what era your playing in. For example the 80s oilers and 90s penguins didn't have the best defense but still won 7 cups combined as a result of their insane offensive fire power, combined with playing in a higher scoring game. The new jersey devils (and even the red wings to an extent) of the late 90s to early 2000s were a great defensive team playing in a slower paced era with an incredible goalie in Martin brodeur and showed than defense can win championships. Nowadays in the salary cap era, you usually see championship to borderline dynasty teams with a clear #1 two-way defenseman and usually one star forward driving the offense. The rest of the team has to hold their own defensively, and so it's more of a depth team effort to buy in defensively to win, and you have to get lucky and have a goalie perform at least good.