I'm sorry but did you even watch Boston play when they won the cup? Thornton, Paille and Campbell all played a role. They chip in when needed and make it tough for the opposing team. Hell look at New Jersey this year with Carter and Bernier leading the charge. 4th liners can do more if you get them the chance.
What he said. Boston's 4th line played a big part of their cup run, they probably are the best 4th line in the league. New Jersey and LA's 4th line were also both dynamite on their cup runs. I love when people say just throw a bunch of plugs on the 4th line who cares.