I'm still of the mindset that you have 3 somewhat proven "duos" that can be relied on to be effective, and in the past have been effective, some in longers samples.
Marchand Bergeron
or Batman and Robin if you want a good comparison.
These guys are chemistry defined. and Bergeron is the steadying influence on Marchand, who I think has super powers that we have only barely seen to this point. The Marchand int 2011 Cup run is who Brad could be all the time, and I think we are going to see him emerge as a much more mature player with a more consistent effort this year. Their defensive prowess is exemplary and when PKing together, it is like they share a brain.
Pastrnak and Spooner
They play the game at the same speed, and compliment each other's creativity and skill set and were the best scoring option on the team in the last 1/3 of the season last year. I am not sure why there is a need to split them up and I would love to see them together again, as they are similar in age, like the first pair above and could become the next generation for Bruins fans. Offensive upside is higher than Bergie and Marchand and both have shown the willingness to work hard on the D side of the puck.
Eriksson and Krecji
Small sample. but they also play the game at a similar speed. Louie gets a bad rap around here but from start to finish last year he was right with Bergie as out best, most productive forward. Krejci makes everyone better, and I think he is going to be motivated top prove that he is not second fiddle to Bergeron. Claude has said it many times, "As David goes, so go the Bruins." Krejci has less experience with any of the other forwards, Pastrnak included. I think it is silly to try to force them together because they both are from the same area or whatever reason there is.
So to me, building around these duos would be the approach to take.
You have Hayes, Connolly and Beleskey to pop in on these lines.
Hayes is a possession and puck protection, go hard to the net and battle for his spot. He is the kind of guy who you won't notice, but who will make space and be involved in all three zones.
Connolly has a high skill level, some speed and grit and willingness to go hard to the net also, and something to prove. Big time.
Beleskey comes touted as a gamer. Lots of grit, in your face, not punishing hitter, but a wear-you-down kind of game, hard forecheck, with decent complimentary skills, and plays all three zones.
For me, at this point, I am going to put Hayes with Bergie and Marchand. HE can add to the cycle and possession game they already play, and he can be the bog body in front. I could see him getting 25 goals in that role.
Connolly, and Beleskey both have a higher revving engine, more speed, and a little more grit. Of the two, I like Connolly with Krejci and Eriksson, and I like Beleskey with Spooner and Pastrnak. Why? Call it a gut feeling.
This means that you have one of Eriksson or Connolly on the off wing. Louie has played off-wing and looked comfortable there.
This is a balanced top 3 lines in my opinion. You give Bergeron's line every start in the D-zone that you can, and keep Spoons starts limited to the Offensive Zone and Krejci gets the NZ and anything in the D-zone when Bergie needs a rest.
That is my lines at the start. I might swap Connolly and Beleskey if "chemistry" isn't there, but that forces one of Pastrnak or Connolly to play off-wing and I don't like that as much as I do Eriksson.
On Defense.. all I can say is after Chara, Krug, and Seidenberg there is a lot of work to be sorted out. C Miller, Trotman and Morrow all appear ready to make the jump to FT big club. McQuaid and K Miller to me are redundant, and we really only need one of them. I LOVED McQuaids fight last night. I know it was against a "star" but he was totally holding back the whole time like a big brother would with a younger sibling. I was laughing at the effort that Oshie was putting up, and Adam was like, "Dude, you don't want to piss me off. Knock it off."
C Miller is going to be a very good player for the Bruins this year if given the chance.