I'm not going to point at particular lines/D-pairs or any particular players, because I believe the problems run deeper than that right now.
The bottom line for me......where is the tight team defensive structure that we've all become accustomed to seeing from this franchise? Since 2007-08, the foundation of this team's success has always been it's defensive structure.
Sweeney and Neely attacked this off-season so the Bruins would once again be a Top 5 defensive team along with an (admittedly) questionable offense.
Instead it's been open season in front of the Bruins goaltenders. Inability to control transition through the neutral zone. Easy zone entries. Running around and losing coverage down low and in front. Going out of their way to make big hits but leaving opposing players open.
Until they fix those issues and get back to being one of the strongest defensive teams in the league, they have no chance of success. Fix that first, and then maybe they can find a way to generate more offense.