I agree with the last sentence that the job of the 4th line is to primarily prevent the other team from scoring, and secondarily to not be a liability out there. But I hate using Stanley Cup champions as a model as how to win. Any given year there are about 10 teams with different styles that realistically have a shot at going all the way. Too many variables like matchups, health, hot steaks, variance, etc to say precisely how a team should be built.