I think it shows how ridiculous a Worcester-based district looks if you insist on keeping two districts to the west of it, but otherwise, it's not absurd. The leader of the committee in charge of redistricting is from Amherst, so I suppose the die is cast about letting western Mass avoid the axe for the third dropped district in a row. My guess is that if the 8th is broken up, instead of connecting Cambridge and Somerville to the 6th as in this map, they get put in the 7th and I have Ed Markey as a Congressman. In that case, the 7th contracts a lot and the 6th picks up some more northern suburbs. I guess the rest of Boston goes to the (current) 9th, which makes for an interesting primary for Steve Lynch.
Assuming Capuano runs for Senate, you might want to give Cambridge to Barney Frank. Frank will likely retire before 2020, and Sean Bielat was extremely strong in 2010. He'll probably be back when the seat is open. Somerville should probably go to Tierney (no need to have Cambridge and Somerville in the same district anymore). Furthermore, you can move Keating's district NW into the Boston suburbs and potentially have a Cape Cod to Fall River seat.
I'm inherently skeptical of any district linking Somerville to Essex County. It's just too much of a stretch, IMO.
I think giving liberal places like Cambridge to Barney Frank's district makes a lot of sense in theory and is what I would do, but when you start putting places like that and Allston-Brighton (that neighborhood northwest of Brookline) in the district, you have too many people to keep a link to New Bedford. All of which is rational if you're making serious revisions to the map, but Massachusetts always goes for the least amount of change, and Frank seems very happy to have New Bedford and southeastern Mass. in his district. I also don't think Bielat is a threat in the long term, his strength this year had to do with the environment and with Frank being a polarizing figure, and Frank still won soundly. The district is quite Dem as it is.
So I agree, ideologically, Cambridge should be in a district with Brookline and Newton, but if we are going with least-change as a guiding force, it causes less disruption to put both Cambridge and Somerville in the 7th with Markey and let him slough off his outer suburban towns to other districts.
And if we were being more rational than that, we'd divide up the 1st district and make minimal tweaks to everything east of Worcester, but I'm going to be whining pointlessly about that to no effect all year.