On a talented and well-balanced hockey team, which the Bruins certainly are, designations of first, second, third and fourth lines are not critically important, since all four trios are expected to make significant contributions. But it would be silly to suggest such labels have no meaning. Just check the paychecks of the players on the four lines and you’ll see how much their teams value each. Going into this season, any analysis of the Bruins would have rated the team’s No. 1 line to be David Krejci centering Milan Lucic and Nathan Horton. Of course, that was the on-paper assessment. On the ice, clearly, the No. 1 line has been Patrice Bergeron with Tyler Seguin and Brad Marchand — a point not lost on Krejci & Co. Well, the Krejci line reminded everyone yesterday that when it’s at its best, it still deserves that No. 1 title. It was in peak form, or at least close enough, as Krejci and Horton both had a goal and two assists, and Lucic had a career-best three assists, as the Bruins delivered one of their top all-around performances in some time in beating the Washington Capitals, 4-1.